Documentation Source Text

  database connections to share the same page and schema cache.
  This feature is useful for certain specialized applications.
}
doc {Tcl API} {tclsqlite.html} {
  A description of the TCL interface bindings for SQLite.
}

doc {How SQLite Implements Atomic Commit} {ac/atomiccommit.html} {
  A description of the logic within SQLite that implements
  transactions with atomic commit, even in the face of power
  failures.
}
doc {Moving From SQLite 3.4 to 3.5} {34to35.html} {
  A document describing the differences between SQLite version 3.4.2
  and 3.5.0.

  database connections to share the same page and schema cache.
  This feature is useful for certain specialized applications.
}
doc {Tcl API} {tclsqlite.html} {
  A description of the TCL interface bindings for SQLite.
}

doc {How SQLite Implements Atomic Commit} {atomiccommit.html} {
  A description of the logic within SQLite that implements
  transactions with atomic commit, even in the face of power
  failures.
}
doc {Moving From SQLite 3.4 to 3.5} {34to35.html} {
  A document describing the differences between SQLite version 3.4.2
  and 3.5.0.

<title>Query Language Understood by SQLite</title>
<tcl>
if 0 {
if {[llength $argv]>0} {
  set outputdir [lindex $argv 0]
} else {
  set outputdir ""
}

puts {
<h1 class="pdf_section">SQL As Understood By SQLite</h1>

<p>The SQLite library understands most of the standard SQL
language.  But it does <a href="omitted.html">omit some features</a>
while at the same time
adding a few features of its own.  This document attempts to
describe precisely what parts of the SQL language SQLite does
and does not support.  A list of <a href="lang_keywords.html">keywords</a> is 
also provided.</p>

................................................................................
<p>This document is just an overview of the SQL syntax implemented
by SQLite.  Many low-level productions are omitted.  For detailed information
on the language that SQLite understands, refer to the source code and
the grammar file "parse.y".</p>

<div class="pdf_ignore">
<p>SQLite implements the follow syntax:</p>
<p><ul>
}



proc slink {label} {
  if {[string match *.html $label]} {
    return $label
  }
  if {[string length $::outputdir]==0} {
    return #$label
  } else { 
    return lang_$label.html
  }
}

foreach {section} [lsort -index 0 -dictionary {
  {{CREATE TABLE} createtable}
  {{CREATE VIRTUAL TABLE} createvtab}
  {{CREATE INDEX} createindex}
  {VACUUM vacuum}
  {{DROP TABLE} droptable}
  {{DROP INDEX} dropindex}
  {INSERT insert}
  {REPLACE replace}
  {DELETE delete}
  {UPDATE update}
  {SELECT select}
  {comment comment}
  {COPY copy}
  {EXPLAIN explain}
  {expression expr}
  {{BEGIN TRANSACTION} transaction}
  {{COMMIT TRANSACTION} transaction}
  {{END TRANSACTION} transaction}
  {{ROLLBACK TRANSACTION} transaction}
  {PRAGMA pragma.html}
................................................................................
  {{ATTACH DATABASE} attach}
  {{DETACH DATABASE} detach}
  {REINDEX reindex}
  {{ALTER TABLE} altertable}
  {{ANALYZE} analyze}
}] {
  foreach {s_title s_tag} $section {}
  puts "<li><a href=\"[slink $s_tag]\">$s_title</a></li>"
}

puts {</ul></p>
</div>

<p>Details on the implementation of each command are provided in
the sequel.</p>
}




proc Operator {name} {
  return "<font color=\"#2c2cf0\"><big>$name</big></font>"
}
proc Nonterminal {name} {
  return "<i><font color=\"#ff3434\">$name</font></i>"
}
proc Keyword {name} {
................................................................................
  return "<font color=\"#2c2cf0\">$name</font>"
}
proc Example {text} {
  puts "<blockquote><pre>$text</pre></blockquote>"
}

proc Section {name label} {
  global outputdir


  if {[string length $outputdir]!=0} {
    if {[llength [info commands puts_standard]]>0} {
      footer $::rcsid
    }

    if {[string length $label]>0} {
      rename puts puts_standard
      proc puts {str} {
        regsub -all {href="#([a-z]+)"} $str {href="lang_\1.html"} str
        puts_standard $::section_file $str
      }
      rename footer footer_standard
      proc footer {id} {
        footer_standard $id
        rename footer ""
        rename puts ""
        rename puts_standard puts
        rename footer_standard footer
      } 
      set ::section_file [open [file join $outputdir lang_$label.html] w]
      header "Query Language Understood by SQLite: $name"
      puts "<h1>SQL As Understood By SQLite</h1>"
      puts "<a href=\"lang.html\">\[Contents\]</a>"
      puts "<h2>$name</h2>"
      return 
    }
  }
  puts "\n<hr />"
  if {$label!=""} {
    puts "<a name=\"$label\"></a>"
  }
  puts "<h1>$name</h1>\n"
}


Section {ALTER TABLE} altertable

Syntax {sql-statement} {
ALTER TABLE [<database-name> .] <table-name> <alteration>
} {alteration} {
RENAME TO <new-table-name>
} {alteration} {
ADD [COLUMN] <column-def>
}


puts {
<p>SQLite's version of the ALTER TABLE command allows the user to 
rename or add a new column to an existing table. It is not possible
to remove a column from a table.
</p>

<p>The RENAME TO syntax is used to rename the table identified by 
<i>[database-name.]table-name</i> to <i>new-table-name</i>. This command 
................................................................................
the amount of data in the table.  The ALTER TABLE command runs as quickly
on a table with 10 million rows as it does on a table with 1 row.
</p>

<p>After ADD COLUMN has been run on a database, that database will not
be readable by SQLite version 3.1.3 and earlier until the database
is <a href="lang_vacuum.html">VACUUM</a>ed.</p>
}



Section {ANALYZE} analyze

Syntax {sql-statement} {
  ANALYZE
}
Syntax {sql-statement} {
  ANALYZE <database-name>
}
Syntax {sql-statement} {
  ANALYZE [<database-name> .] <table-name>
}


puts {
<p>The ANALYZE command gathers statistics about indices and stores them
in a special tables in the database where the query optimizer can use
them to help make better index choices.
If no arguments are given, all indices in all attached databases are
analyzed.  If a database name is given as the argument, all indices
in that one database are analyzed.  If the argument is a table name,
then only indices associated with that one table are analyzed.</p>
................................................................................
<p>The initial implementation stores all statistics in a single
table named <b>sqlite_stat1</b>.  Future enhancements may create
additional tables with the same name pattern except with the "1"
changed to a different digit.  The <b>sqlite_stat1</b> table cannot
be <a href="#droptable">DROP</a>ped,
but all the content can be <a href="#delete">DELETE</a>d which has the
same effect.</p>
}


Section {ATTACH DATABASE} attach

Syntax {sql-statement} {
ATTACH [DATABASE] <database-filename> AS <database-name>
}


puts {
<p>The ATTACH DATABASE statement adds another database 
file to the current database connection.  If the filename contains 
punctuation characters it must be quoted.  The names 'main' and 
'temp' refer to the main database and the database used for 
temporary tables.  These cannot be detached.  Attached databases 
are removed using the <a href="#detach">DETACH DATABASE</a> 
statement.</p>
................................................................................
might not.
Atomic commit of attached databases is a new feature of SQLite version 3.0.
In SQLite version 2.8, all commits to attached databases behaved as if
the main database were ":memory:".
</p>

<p>There is a compile-time limit of 10 attached database files.</p>
}




Section {BEGIN TRANSACTION} transaction

Syntax {sql-statement} {
BEGIN [ DEFERRED | IMMEDIATE | EXCLUSIVE ] [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
END [TRANSACTION [<name>]]
................................................................................
}
Syntax {sql-statement} {
COMMIT [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
ROLLBACK [TRANSACTION [<name>]]
}

puts {

<p>
No changes can be made to the database except within a transaction.
Any command that changes the database (basically, any SQL command
other than SELECT) will automatically start a transaction if
one is not already in effect.  Automatically started transactions
are committed at the conclusion of the command.
................................................................................
error, but no harm is caused by this.</p>

<p>Future versions of SQLite may extend the list of errors which
might cause automatic transaction rollback.  Future versions of
SQLite might change the error response.  In particular, we may
choose to simplify the interface in future versions of SQLite by
causing the errors above to force an unconditional rollback.</p>
}




Section comment comment

Syntax {comment} {<SQL-comment> | <C-comment>
} {SQL-comment} {-- <single-line>
} {C-comment} {/STAR <multiple-lines> [STAR/]
}


puts {
<p> Comments aren't SQL commands, but can occur in SQL queries. They are 
treated as whitespace by the parser.  They can begin anywhere whitespace 
can be found, including inside expressions that span multiple lines.
</p>

<p> SQL comments only extend to the end of the current line.</p>

................................................................................
<p> C comments can span any number of lines.  If there is no terminating
delimiter, they extend to the end of the input.  This is not treated as
an error.  A new SQL statement can begin on a line after a multiline
comment ends.  C comments can be embedded anywhere whitespace can occur,
including inside expressions, and in the middle of other SQL statements.
C comments do not nest.  SQL comments inside a C comment will be ignored.
</p>
}


Section COPY copy

Syntax {sql-statement} {
COPY [ OR <conflict-algorithm> ] [<database-name> .] <table-name> FROM <filename>
[ USING DELIMITERS <delim> ]
}

puts {
<p>The COPY command is available in SQLite version 2.8 and earlier.
The COPY command has been removed from SQLite version 3.0 due to
complications in trying to support it in a mixed UTF-8/16 environment.
In version 3.0, the <a href="sqlite.html">command-line shell</a>
contains a new command <b>.import</b> that can be used as a substitute
for COPY.
</p>

<p>The COPY command is an extension used to load large amounts of
data into a table.  It is modeled after a similar command found
in PostgreSQL.  In fact, the SQLite COPY command is specifically
designed to be able to read the output of the PostgreSQL dump
utility <b>pg_dump</b> so that data can be easily transferred from
PostgreSQL into SQLite.</p>

<p>The table-name is the name of an existing table which is to
be filled with data.  The filename is a string or identifier that
names a file from which data will be read.  The filename can be
the <b>STDIN</b> to read data from standard input.</p>

<p>Each line of the input file is converted into a single record
in the table.  Columns are separated by tabs.  If a tab occurs as
data within a column, then that tab is preceded by a baskslash "\"
character.  A baskslash in the data appears as two backslashes in
a row.  The optional USING DELIMITERS clause can specify a delimiter
other than tab.</p>

<p>If a column consists of the character "\N", that column is filled
with the value NULL.</p>

<p>The optional conflict-clause allows the specification of an alternative
constraint conflict resolution algorithm to use for this one command.
See the section titled
<a href="#conflict">ON CONFLICT</a> for additional information.</p>

<p>When the input data source is STDIN, the input can be terminated
by a line that contains only a baskslash and a dot:}
puts "\"[Operator \\.]\".</p>"




Section {CREATE INDEX} createindex

Syntax {sql-statement} {
CREATE [UNIQUE] INDEX [IF NOT EXISTS] [<database-name> .] <index-name> 
ON <table-name> ( <column-name> [, <column-name>]* )
} {column-name} {
<name> [ COLLATE <collation-name>] [ ASC | DESC ]
}


puts {
<p>The CREATE INDEX command consists of the keywords "CREATE INDEX" followed
by the name of the new index, the keyword "ON", the name of a previously
created table that is to be indexed, and a parenthesized list of names of
columns in the table that are used for the index key.
Each column name can be followed by one of the "ASC" or "DESC" keywords
to indicate sort order, but the sort order is ignored in the current
implementation.  Sorting is always done in ascending order.</p>
................................................................................
SQLite's internal representation of the index layout.</p>

<p>If the optional IF NOT EXISTS clause is present and another index
with the same name aleady exists, then this command becomes a no-op.</p>

<p>Indexes are removed with the <a href="#dropindex">DROP INDEX</a> 
command.</p>
}




Section {CREATE TABLE} {createtable}

Syntax {sql-command} {
CREATE [TEMP | TEMPORARY] TABLE [IF NOT EXISTS] [<database-name> .] <table-name> (
  <column-def> [, <column-def>]*
  [, <constraint>]*
)
................................................................................
} {constraint} {
PRIMARY KEY ( <column-list> ) [ <conflict-clause> ] |
UNIQUE ( <column-list> ) [ <conflict-clause> ] |
CHECK ( <expr> )
} {conflict-clause} {
ON CONFLICT <conflict-algorithm>
}


puts {
<p>A CREATE TABLE statement is basically the keywords "CREATE TABLE"
followed by the name of a new table and a parenthesized list of column
definitions and constraints.  The table name can be either an identifier
or a string.  Tables names that begin with "<b>sqlite_</b>" are reserved
for use by the engine.</p>

<p>Each column definition is the name of the column followed by the
................................................................................
that has datatype INTEGER, then that column is used internally
as the actual key of the B-Tree for the table.  This means that the column
may only hold unique integer values.  (Except for this one case,
SQLite ignores the datatype specification of columns and allows
any kind of data to be put in a column regardless of its declared
datatype.)  If a table does not have an INTEGER PRIMARY KEY column,
then the B-Tree key will be a automatically generated integer.
<a name="rowid"> The
B-Tree key for a row can always be accessed using one of the
special names "<b>ROWID</b>", "<b>OID</b>", or "<b>_ROWID_</b>".
This is true regardless of whether or not there is an INTEGER
PRIMARY KEY.  An INTEGER PRIMARY KEY column can also include the
keyword AUTOINCREMENT.  The AUTOINCREMENT keyword modified the way
that B-Tree keys are automatically generated.  Additional detail
on automatic B-Tree key generation is available
................................................................................
</p>

<p>If the optional IF NOT EXISTS clause is present and another table
with the same name aleady exists, then this command becomes a no-op.</p>

<p>Tables are removed using the <a href="#droptable">DROP TABLE</a> 
statement.  </p>
}




Section {CREATE TRIGGER} createtrigger

Syntax {sql-statement} {
CREATE [TEMP | TEMPORARY] TRIGGER [IF NOT EXISTS] <trigger-name> [ BEFORE | AFTER ]
<database-event> ON [<database-name> .] <table-name>
<trigger-action>
}
................................................................................
END
}

Syntax {trigger-step} {
<update-statement> | <insert-statement> | 
<delete-statement> | <select-statement> 
}


puts {
<p>The CREATE TRIGGER statement is used to add triggers to the 
database schema. Triggers are database operations (the <i>trigger-action</i>) 
that are automatically performed when a specified database event (the
<i>database-event</i>) occurs.  </p>

<p>A trigger may be specified to fire whenever a DELETE, INSERT or UPDATE of a
particular database table occurs, or whenever an UPDATE of one or more
................................................................................

<p><b>Example:</b></p>

<p>Assuming that customer records are stored in the "customers" table, and
that order records are stored in the "orders" table, the following trigger
ensures that all associated orders are redirected when a customer changes
his or her address:</p>
}
Example {
CREATE TRIGGER update_customer_address UPDATE OF address ON customers 
  BEGIN
    UPDATE orders SET address = new.address WHERE customer_name = old.name;
  END;

}
puts {
<p>With this trigger installed, executing the statement:</p>
}

Example {
UPDATE customers SET address = '1 Main St.' WHERE name = 'Jack Jones';

}
puts {
<p>causes the following to be automatically executed:</p>
}
Example {
UPDATE orders SET address = '1 Main St.' WHERE customer_name = 'Jack Jones';

}

puts {
<p>Note that currently, triggers may behave oddly when created on tables
  with INTEGER PRIMARY KEY fields. If a BEFORE trigger program modifies the 
  INTEGER PRIMARY KEY field of a row that will be subsequently updated by the
  statement that causes the trigger to fire, then the update may not occur. 
  The workaround is to declare the table with a PRIMARY KEY column instead
  of an INTEGER PRIMARY KEY column.</p>
}

puts {
<p>A special SQL function RAISE() may be used within a trigger-program, with the following syntax</p> 
}


Syntax {raise-function} {
RAISE ( ABORT, <error-message> ) | 
RAISE ( FAIL, <error-message> ) | 
RAISE ( ROLLBACK, <error-message> ) | 
RAISE ( IGNORE )
}
puts {

<p>When one of the first three forms is called during trigger-program execution, the specified ON CONFLICT processing is performed (either ABORT, FAIL or 
 ROLLBACK) and the current query terminates. An error code of SQLITE_CONSTRAINT is returned to the user, along with the specified error message.</p>

<p>When RAISE(IGNORE) is called, the remainder of the current trigger program,
the statement that caused the trigger program to execute and any subsequent
    trigger programs that would of been executed are abandoned. No database
    changes are rolled back.  If the statement that caused the trigger program
    to execute is itself part of a trigger program, then that trigger program
    resumes execution at the beginning of the next step.
</p>

<p>Triggers are removed using the <a href="#droptrigger">DROP TRIGGER</a>
statement.</p>
}




Section {CREATE VIEW} {createview}

Syntax {sql-command} {
CREATE [TEMP | TEMPORARY] VIEW [IF NOT EXISTS] [<database-name>.] <view-name> AS <select-statement>
}


puts {
<p>The CREATE VIEW command assigns a name to a pre-packaged 
<a href="#select">SELECT</a>
statement.  Once the view is created, it can be used in the FROM clause
of another SELECT in place of a table name.
</p>

<p>If the "TEMP" or "TEMPORARY" keyword occurs in between "CREATE"
................................................................................
the table is created in the main database.</p>

<p>You cannot COPY, DELETE, INSERT or UPDATE a view.  Views are read-only 
in SQLite.  However, in many cases you can use a <a href="#createtrigger">
TRIGGER</a> on the view to accomplish the same thing.  Views are removed 
with the <a href="#dropview">DROP VIEW</a> 
command.</p>
}



Section {CREATE VIRTUAL TABLE} {createvtab}

Syntax {sql-command} {
CREATE VIRTUAL TABLE [<database-name> .] <table-name> USING <module-name> [( <arguments> )]
}


puts {
<p>A virtual table is an interface to an external storage or computation
engine that appears to be a table but does not actually store information
in the database file.</p>

<p>In general, you can do anything with a virtual table that can be done
with an ordinary table, except that you cannot create triggers on a
virtual table.  Some virtual table implementations might impose additional
................................................................................
SQLite passes the module arguments directly
to the module without any interpretation.  It is the responsibility
of the module implementation to parse and interpret its own arguments.</p>

<p>A virtual table is destroyed using the ordinary
<a href="#droptable">DROP TABLE</a> statement.  There is no
DROP VIRTUAL TABLE statement.</p>
}



Section DELETE delete

Syntax {sql-statement} {
DELETE FROM [<database-name> .] <table-name> [WHERE <expr>]
}


puts {
<p>The DELETE command is used to remove records from a table.
The command consists of the "DELETE FROM" keywords followed by
the name of the table from which records are to be removed.
</p>

<p>Without a WHERE clause, all rows of the table are removed.
If a WHERE clause is supplied, then only those rows that match
the expression are removed.</p>
}




Section {DETACH DATABASE} detach

Syntax {sql-command} {
DETACH [DATABASE] <database-name>
}


puts {
<p>This statement detaches an additional database connection previously 
attached using the <a href="#attach">ATTACH DATABASE</a> statement.  It
is possible to have the same database file attached multiple times using 
different names, and detaching one connection to a file will leave the 
others intact.</p>

<p>This statement will fail if SQLite is in the middle of a transaction.</p>
}




Section {DROP INDEX} dropindex

Syntax {sql-command} {
DROP INDEX [IF EXISTS] [<database-name> .] <index-name>
}


puts {
<p>The DROP INDEX statement removes an index added
with the <a href="#createindex">
CREATE INDEX</a> statement.  The index named is completely removed from
the disk.  The only way to recover the index is to reenter the
appropriate CREATE INDEX command.</p>

<p>The DROP INDEX statement does not reduce the size of the database 
file in the default mode.
Empty space in the database is retained for later INSERTs.  To 
remove free space in the database, use the <a href="#vacuum">VACUUM</a> 
command.  If AUTOVACUUM mode is enabled for a database then space
will be freed automatically by DROP INDEX.</p>
}




Section {DROP TABLE} droptable

Syntax {sql-command} {
DROP TABLE [IF EXISTS] [<database-name>.] <table-name>
}


puts {
<p>The DROP TABLE statement removes a table added with the <a href=
"#createtable">CREATE TABLE</a> statement.  The name specified is the
table name.  It is completely removed from the database schema and the 
disk file.  The table can not be recovered.  All indices associated 
with the table are also deleted.</p>

<p>The DROP TABLE statement does not reduce the size of the database 
................................................................................
later INSERTs.  To 
remove free space in the database, use the <a href="#vacuum">VACUUM</a> 
command.  If AUTOVACUUM mode is enabled for a database then space
will be freed automatically by DROP TABLE.</p>

<p>The optional IF EXISTS clause suppresses the error that would normally
result if the table does not exist.</p>
}




Section {DROP TRIGGER} droptrigger
Syntax {sql-statement} {
DROP TRIGGER [IF EXISTS] [<database-name> .] <trigger-name>
}
puts { 

<p>The DROP TRIGGER statement removes a trigger created by the 
<a href="#createtrigger">CREATE TRIGGER</a> statement.  The trigger is 
deleted from the database schema. Note that triggers are automatically 
dropped when the associated table is dropped.</p>
}




Section {DROP VIEW} dropview

Syntax {sql-command} {
DROP VIEW [IF EXISTS] <view-name>
}


puts {
<p>The DROP VIEW statement removes a view created by the <a href=
"#createview">CREATE VIEW</a> statement.  The name specified is the 
view name.  It is removed from the database schema, but no actual data 
in the underlying base tables is modified.</p>
}




Section EXPLAIN explain

Syntax {sql-statement} {
EXPLAIN <sql-statement>
}


puts {
<p>The EXPLAIN command modifier is a non-standard extension.  The
idea comes from a similar command found in PostgreSQL, but the operation
is completely different.</p>

<p>If the EXPLAIN keyword appears before any other SQLite SQL command
then instead of actually executing the command, the SQLite library will
report back the sequence of virtual machine instructions it would have
used to execute the command had the EXPLAIN keyword not been present.
For additional information about virtual machine instructions see
the <a href="arch.html">architecture description</a> or the documentation
on <a href="opcode.html">available opcodes</a> for the virtual machine.</p>
}




Section expression expr

Syntax {expr} {
<expr> <binary-op> <expr> |
<expr> [NOT] <like-op> <expr> [ESCAPE <expr>] |
<unary-op> <expr> |
( <expr> ) |
................................................................................
[EXISTS] ( <select-statement> ) |
CASE [<expr>] LP WHEN <expr> THEN <expr> RPPLUS [ELSE <expr>] END |
CAST ( <expr> AS <type> ) |
<expr> COLLATE <collation-name>
} {like-op} {
LIKE | GLOB | REGEXP | MATCH
}


puts {
<p>This section is different from the others.  Most other sections of
this document talks about a particular SQL command.  This section does
not talk about a standalone command but about "expressions" which are 
subcomponents of most other commands.</p>

<p>SQLite understands the following binary operators, in order from
highest to lowest precedence:</p>
................................................................................
any binary operator.</p>

<p>The unary operator [Operator +] is a no-op.  It can be applied
to strings, numbers, or blobs and it always gives as its result the
value of the operand.</p>

<p>Note that there are two variations of the equals and not equals
operators.  Equals can be either}


puts "[Operator =] or [Operator ==].
The non-equals operator can be either
[Operator !=] or [Operator {&lt;&gt;}].
The [Operator ||] operator is \"concatenate\" - it joins together
the two strings of its operands.
The operator [Operator %] outputs the remainder of its left 
operand modulo its right operand.</p>

<p>The result of any binary operator is a numeric value, except
for the [Operator ||] concatenation operator which gives a string
result.</p>"

puts {

<a name="literal_value"></a>
<p>
A literal value is an integer number or a floating point number.
Scientific notation is supported.  The "." character is always used
as the decimal point even if the locale setting specifies "," for
this role - the use of "," for the decimal point would result in
................................................................................
<a href="capi3ref.html#sqlite3_bind_int">sqlite3_bind</a> are treated
as NULL.</p>

<a name="like"></a>
<p>The LIKE operator does a pattern matching comparison. The operand
to the right contains the pattern, the left hand operand contains the
string to match against the pattern. 
}
puts "A percent symbol [Operator %] in the pattern matches any
sequence of zero or more characters in the string.  An underscore
[Operator _] in the pattern matches any single character in the
string.  Any other character matches itself or it's lower/upper case
equivalent (i.e. case-insensitive matching).  (A bug: SQLite only
understands upper/lower case for 7-bit Latin characters.  Hence the
LIKE operator is case sensitive for 8-bit iso8859 characters or UTF-8
characters.  For example, the expression <b>'a'&nbsp;LIKE&nbsp;'A'</b>
is TRUE but <b>'&aelig;'&nbsp;LIKE&nbsp;'&AElig;'</b> is FALSE.).</p>"

puts {
<p>If the optional ESCAPE clause is present, then the expression
following the ESCAPE keyword must evaluate to a string consisting of
a single character. This character may be used in the LIKE pattern
to include literal percent or underscore characters. The escape
character followed by a percent symbol, underscore or itself matches a
literal percent symbol, underscore or escape character in the string,
respectively. The infix LIKE operator is implemented by calling the
user function <a href="#likeFunc"> like(<i>X</i>,<i>Y</i>)</a>.</p>
}

puts {
The LIKE operator is not case sensitive and will match upper case
characters on one side against lower case characters on the other.  
(A bug: SQLite only understands upper/lower case for 7-bit Latin
characters.  Hence the LIKE operator is case sensitive for 8-bit
iso8859 characters or UTF-8 characters.  For example, the expression
<b>'a'&nbsp;LIKE&nbsp;'A'</b> is TRUE but
<b>'&aelig;'&nbsp;LIKE&nbsp;'&AElig;'</b> is FALSE.).</p>
................................................................................
<td valign="top">Return a copy of the first non-NULL argument.  If
both arguments are NULL then NULL is returned. This behaves the same as 
<b>coalesce()</b> above.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="hexFunc">
hex(<i>X</i>)</td>
<td valign="top">The argument is interpreted as a BLOB.  The result
is a hexadecimal rendering of the content of that blob.</td>
</tr>

<tr>
<td valign="top" align="right">last_insert_rowid()</td>
................................................................................
converted to lower case.  The C library <b>tolower()</b> routine is used
for the conversion, which means that this function might not
work correctly on UTF-8 characters.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="ltrimFunc">
ltrim(<i>X</i>)<br>ltrim(<i>X</i>,<i>Y</i>)</td>
<td valign="top">Return a string formed by removing any and all
characters that appear in <i>Y</i> from the left side of <i>X</i>.
If the <i>Y</i> argument is omitted, spaces are removed.</td>
</tr>


................................................................................
<td valign="top" align="right">random(*)</td>
<td valign="top">Return a pseudo-random integer
between -9223372036854775808 and +9223372036854775807.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="replaceFunc">
replace(<i>X</i>,<i>Y</i>,<i>Z</i>)</td>
<td valign="top">Return a string formed by substituting string <i>Z</i> for
every occurrance of string <i>Y</i> in string <i>X</i>.  The BINARY
collating sequence is used for comparisons.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="randomblobFunc">
randomblob(<i>N</i>)</td>
<td valign="top">Return a <i>N</i>-byte blob containing pseudo-random bytes.
<i>N</i> should be a postive integer.</td>
</tr>

<tr>
<td valign="top" align="right">round(<i>X</i>)<br>round(<i>X</i>,<i>Y</i>)</td>
................................................................................
<td valign="top">Round off the number <i>X</i> to <i>Y</i> digits to the
right of the decimal point.  If the <i>Y</i> argument is omitted, 0 is 
assumed.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="rtrimFunc">
rtrim(<i>X</i>)<br>rtrim(<i>X</i>,<i>Y</i>)</td>
<td valign="top">Return a string formed by removing any and all
characters that appear in <i>Y</i> from the right side of <i>X</i>.
If the <i>Y</i> argument is omitted, spaces are removed.</td>
</tr>

<tr>
................................................................................
right rather than the left.  If <i>X</i> is string
then characters indices refer to actual UTF-8 characters.  If
<i>X</i> is a BLOB then the indices refer to bytes.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="trimFunc">
trim(<i>X</i>)<br>trim(<i>X</i>,<i>Y</i>)</td>
<td valign="top">Return a string formed by removing any and all
characters that appear in <i>Y</i> from both ends of <i>X</i>.
If the <i>Y</i> argument is omitted, spaces are removed.</td>
</tr>


................................................................................
upper-case letters.  The implementation of this function uses the C library
routine <b>toupper()</b> which means it may not work correctly on 
UTF-8 strings.</td>
</tr>

<tr>
<td valign="top" align="right">zeroblob(<i>N</i>)</td>
<td valign="top"><a name="zeroblob">
Return a BLOB consisting of N bytes of 0x00.  SQLite
manages these zeroblobs very efficiently.  Zeroblobs can be used to
reserve space for a BLOB that is later written using 
<a href="capi3ref.html#sqlite3_blob_open">incremental BLOB I/O</a>.</td>
</tr>

</table>
................................................................................

   <p>Sum() will throw an "integer overflow" exception if all inputs
   are integers or NULL
   and an integer overflow occurs at any point during the computation.
   Total() never throws an exception.</p>
</tr>
</table>
}




Section INSERT insert

Syntax {sql-statement} {
INSERT [OR <conflict-algorithm>] INTO [<database-name> .] <table-name> [(<column-list>)] VALUES(<value-list>) |
INSERT [OR <conflict-algorithm>] INTO [<database-name> .] <table-name> [(<column-list>)] <select-statement>
}


puts {
<p>The INSERT statement comes in two basic forms.  The first form
(with the "VALUES" keyword) creates a single new row in an existing table.
If no column-list is specified then the number of values must
be the same as the number of columns in the table.  If a column-list
is specified, then the number of values must match the number of
specified columns.  Columns of the table that do not appear in the
column list are filled with the default value, or with NULL if no
................................................................................
<p>The optional conflict-clause allows the specification of an alternative
constraint conflict resolution algorithm to use during this one command.
See the section titled
<a href="#conflict">ON CONFLICT</a> for additional information.
For compatibility with MySQL, the parser allows the use of the
single keyword <a href="#replace">REPLACE</a> as an alias for "INSERT OR REPLACE".
</p>
}




Section {ON CONFLICT clause} conflict

Syntax {conflict-clause} {
ON CONFLICT <conflict-algorithm>
} {conflict-algorithm} {
ROLLBACK | ABORT | FAIL | IGNORE | REPLACE
}


puts {
<p>The ON CONFLICT clause is not a separate SQL command.  It is a
non-standard clause that can appear in many other SQL commands.
It is given its own section in this document because it is not
part of standard SQL and therefore might not be familiar.</p>

<p>The syntax for the ON CONFLICT clause is as shown above for
the CREATE TABLE command.  For the INSERT and
................................................................................
satisfy a constraint, it does not invoke delete triggers on those
rows.  This behavior might change in a future release.</p>
</dl>

<p>The algorithm specified in the OR clause of a INSERT or UPDATE
overrides any algorithm specified in a CREATE TABLE.
If no algorithm is specified anywhere, the ABORT algorithm is used.</p>
}



Section REINDEX reindex

Syntax {sql-statement} {
  REINDEX <collation name>
}
Syntax {sql-statement} {
  REINDEX [<database-name> .] <table/index-name>
}


puts {
<p>The REINDEX command is used to delete and recreate indices from scratch.
This is useful when the definition of a collation sequence has changed.
</p>

<p>In the first form, all indices in all attached databases that use the
named collation sequence are recreated. In the second form, if 
<i>[database-name.]table/index-name</i> identifies a table, then all indices
................................................................................
</p>

<p>If no <i>database-name</i> is specified and there exists both a table or
index and a collation sequence of the specified name, then indices associated
with the collation sequence only are reconstructed. This ambiguity may be
dispelled by always specifying a <i>database-name</i> when reindexing a
specific table or index.
}



Section REPLACE replace

Syntax {sql-statement} {
REPLACE INTO [<database-name> .] <table-name> [( <column-list> )] VALUES ( <value-list> ) |
REPLACE INTO [<database-name> .] <table-name> [( <column-list> )] <select-statement>
}


puts {
<p>The REPLACE command is an alias for the "INSERT OR REPLACE" variant
of the <a href="#insert">INSERT</a> command.  This alias is provided for
compatibility with MySQL.  See the 
<a href="#insert">INSERT</a> command documentation for additional
information.</p>  
}




Section SELECT select

Syntax {sql-statement} {
SELECT [ALL | DISTINCT] <result> [FROM <table-list>]
[WHERE <expr>]
[GROUP BY <expr-list>]
[HAVING <expr>]
................................................................................
} {sort-expr-list} {
<expr> [<sort-order>] [, <expr> [<sort-order>]]*
} {sort-order} {
[ COLLATE <collation-name> ] [ ASC | DESC ]
} {compound_op} {
UNION | UNION ALL | INTERSECT | EXCEPT
}


puts {
<p>The SELECT statement is used to query the database.  The
result of a SELECT is zero or more rows of data where each row
has a fixed number of columns.  The number of columns in the
result is specified by the expression list in between the
SELECT and FROM keywords.  Any arbitrary expression can be used
as a result.  If a result expression is }
puts "[Operator *] then all columns of all tables are substituted"
................................................................................
operators combine the results of the SELECTs to the right and left into
a single big table.  The difference is that in UNION all result rows
are distinct where in UNION ALL there may be duplicates.
The INTERSECT operator takes the intersection of the results of the
left and right SELECTs.  EXCEPT takes the result of left SELECT after
removing the results of the right SELECT.  When three or more SELECTs
are connected into a compound, they group from left to right.</p>
}




Section UPDATE update

Syntax {sql-statement} {
UPDATE [ OR <conflict-algorithm> ] [<database-name> .] <table-name>
SET <assignment> [, <assignment>]*
[WHERE <expr>]
} {assignment} {
<column-name> = <expr>
}


puts {
<p>The UPDATE statement is used to change the value of columns in 
selected rows of a table.  Each assignment in an UPDATE specifies
a column name to the left of the equals sign and an arbitrary expression
to the right.  The expressions may use the values of other columns.
All expressions are evaluated before any assignments are made.
A WHERE clause can be used to restrict which rows are updated.</p>

<p>The optional conflict-clause allows the specification of an alternative
constraint conflict resolution algorithm to use during this one command.
See the section titled
<a href="#conflict">ON CONFLICT</a> for additional information.</p>
}




Section VACUUM vacuum

Syntax {sql-statement} {
VACUUM [<index-or-table-name>]
}


puts {
<p>The VACUUM command is an SQLite extension modeled after a similar
command found in PostgreSQL.  If VACUUM is invoked with the name of a
table or index then it is suppose to clean up the named table or index.
In version 1.0 of SQLite, the VACUUM command would invoke 
<b>gdbm_reorganize()</b> to clean up the backend database file.</p>

<p>
VACUUM became a no-op when the GDBM backend was removed from
SQLITE in version 2.0.0.
VACUUM was reimplemented in version 2.8.1.
The index or table name argument is now ignored.
</p>

<p>When an object (table, index, or trigger) is dropped from the 
database, it leaves behind empty space.  This makes the database 
file larger than it needs to be, but can speed up inserts.  In time 
inserts and deletes can leave the database file structure fragmented, 
which slows down disk access to the database contents.
................................................................................
<a href="pragma.html#pragma_auto_vacuum">auto_vacuum pragma</a>.
When auto-vacuum is enabled for a database, large deletes cause
the size of the database file to shrink.  However, auto-vacuum
also causes excess fragmentation of the database file.  And auto-vacuum
does not compact partially filled pages of the database as VACUUM
does.
</p>
}



# A list of keywords.  A asterisk occurs after the keyword if it is on
# the fallback list.
#
set keyword_list [lsort {
   ABORT*
   ADD
   AFTER*
................................................................................
   VALUES
   VIEW*
   VIRTUAL*
   WHEN
   WHERE
}]



puts {<DIV class="pdf_section">}
Section {SQLite Keywords} keywords 
puts {</DIV>}


puts {
<p>The SQL standard specifies a huge number of keywords which may not
be used as the names of tables, indices, columns, databases, user-defined
functions, collations, virtual table modules, or any other named object.
The list of keywords is so long that few people can remember them all.
For most SQL code, your safest bet is to never use any English language
word as the name of a user-defined object.</p>

................................................................................
The following are the keywords currently recognized by SQLite:
</p>

<blockquote>
<table width="100%" class="pdf_keywords">
<tr>
<td align="left" valign="top" width="20%">
}


set n [llength $keyword_list]
set nCol 5
set nRow [expr {($n+$nCol-1)/$nCol}]
set i 0
foreach word $keyword_list {
  if {[string index $word end]=="*"} {
    set word [string range $word 0 end-1]
................................................................................
    puts "</td><td valign=\"top\" align=\"left\" width=\"20%\">"
    set i 1
  } else {
    incr i
  }
  puts "<$font>$word</$font><br>"
}

puts {
</td></tr></table></blockquote>

<h2>Special names</h2>

<p>The following are not keywords in SQLite, but are used as names of 
system objects.  They can be used as an identifier for a different 
type of object.</p>
................................................................................
  OID<br>
  ROWID<br>
  SQLITE_MASTER<br>
  SQLITE_SEQUENCE<br>
  SQLITE_TEMP_MASTER<br>
  TEMP<br>
</b></blockquote>
}

puts {<DIV class="pdf_ignore">}
footer $rcsid
if {[string length $outputdir]} {
  footer $rcsid
}
puts {</DIV>}
}
</tcl>

<title>Query Language Understood by SQLite</title>









<h2 class="pdf_section">SQL As Understood By SQLite</h2>

<p>SQLite understands most of the standard SQL
language.  But it does <a href="omitted.html">omit some features</a>
while at the same time
adding a few features of its own.  This document attempts to
describe precisely what parts of the SQL language SQLite does
and does not support.  A list of <a href="lang_keywords.html">keywords</a> is 
also provided.</p>

................................................................................
<p>This document is just an overview of the SQL syntax implemented
by SQLite.  Many low-level productions are omitted.  For detailed information
on the language that SQLite understands, refer to the source code and
the grammar file "parse.y".</p>

<div class="pdf_ignore">
<p>SQLite implements the follow syntax:</p>


<table width="100%" cellpadding="5" border="0">
<tr><td valign="top"><ul>


<tcl>
set i 0








foreach {section} [lsort -index 0 -dictionary {
  {{CREATE TABLE} createtable}
  {{CREATE VIRTUAL TABLE} createvtab}
  {{CREATE INDEX} createindex}
  {VACUUM vacuum}
  {{DROP TABLE} droptable}
  {{DROP INDEX} dropindex}
  {INSERT insert}
  {REPLACE replace}
  {DELETE delete}
  {UPDATE update}
  {SELECT select}
  {comment comment}

  {EXPLAIN explain}
  {expression expr}
  {{BEGIN TRANSACTION} transaction}
  {{COMMIT TRANSACTION} transaction}
  {{END TRANSACTION} transaction}
  {{ROLLBACK TRANSACTION} transaction}
  {PRAGMA pragma.html}
................................................................................
  {{ATTACH DATABASE} attach}
  {{DETACH DATABASE} detach}
  {REINDEX reindex}
  {{ALTER TABLE} altertable}
  {{ANALYZE} analyze}
}] {
  foreach {s_title s_tag} $section {}
  puts "<li><a href=\"lang_$s_tag.html\">$s_title</a></li>"

  incr i
  if {$i==15} {
    puts "</ul></td><td valign=\"top\"><ul>"
  }


}
</tcl>
</ul></td></tr></table>

<tcl>
proc Operator {name} {
  return "<font color=\"#2c2cf0\"><big>$name</big></font>"
}
proc Nonterminal {name} {
  return "<i><font color=\"#ff3434\">$name</font></i>"
}
proc Keyword {name} {
................................................................................
  return "<font color=\"#2c2cf0\">$name</font>"
}
proc Example {text} {
  puts "<blockquote><pre>$text</pre></blockquote>"
}

proc Section {name label} {
  global OUT DOC DEST

  PutsFooter $DOC/pages/lang.in
  close $OUT
  set OUT [open $DEST/lang_$label.html w]
  PutsHeader "SQLite Query Language: $name"


















  puts {<a href="lang.html"><h2>SQL As Understood By SQLite</h2></a>}

  puts "<h3>$name</h3>"

}








###############################################################################
Section {ALTER TABLE} altertable

Syntax {sql-statement} {
ALTER TABLE [<database-name> .] <table-name> <alteration>
} {alteration} {
RENAME TO <new-table-name>
} {alteration} {
ADD [COLUMN] <column-def>
}
</tcl>


<p>SQLite's version of the ALTER TABLE command allows the user to 
rename or add a new column to an existing table. It is not possible
to remove a column from a table.
</p>

<p>The RENAME TO syntax is used to rename the table identified by 
<i>[database-name.]table-name</i> to <i>new-table-name</i>. This command 
................................................................................
the amount of data in the table.  The ALTER TABLE command runs as quickly
on a table with 10 million rows as it does on a table with 1 row.
</p>

<p>After ADD COLUMN has been run on a database, that database will not
be readable by SQLite version 3.1.3 and earlier until the database
is <a href="lang_vacuum.html">VACUUM</a>ed.</p>


<tcl>
##############################################################################
Section {ANALYZE} analyze

Syntax {sql-statement} {
  ANALYZE
}
Syntax {sql-statement} {
  ANALYZE <database-name>
}
Syntax {sql-statement} {
  ANALYZE [<database-name> .] <table-name>
}
</tcl>


<p>The ANALYZE command gathers statistics about indices and stores them
in a special tables in the database where the query optimizer can use
them to help make better index choices.
If no arguments are given, all indices in all attached databases are
analyzed.  If a database name is given as the argument, all indices
in that one database are analyzed.  If the argument is a table name,
then only indices associated with that one table are analyzed.</p>
................................................................................
<p>The initial implementation stores all statistics in a single
table named <b>sqlite_stat1</b>.  Future enhancements may create
additional tables with the same name pattern except with the "1"
changed to a different digit.  The <b>sqlite_stat1</b> table cannot
be <a href="#droptable">DROP</a>ped,
but all the content can be <a href="#delete">DELETE</a>d which has the
same effect.</p>


<tcl>
Section {ATTACH DATABASE} attach

Syntax {sql-statement} {
ATTACH [DATABASE] <database-filename> AS <database-name>
}
</tcl>


<p>The ATTACH DATABASE statement adds another database 
file to the current database connection.  If the filename contains 
punctuation characters it must be quoted.  The names 'main' and 
'temp' refer to the main database and the database used for 
temporary tables.  These cannot be detached.  Attached databases 
are removed using the <a href="#detach">DETACH DATABASE</a> 
statement.</p>
................................................................................
might not.
Atomic commit of attached databases is a new feature of SQLite version 3.0.
In SQLite version 2.8, all commits to attached databases behaved as if
the main database were ":memory:".
</p>

<p>There is a compile-time limit of 10 attached database files.</p>



<tcl>
###############################################################################
Section {BEGIN TRANSACTION} transaction

Syntax {sql-statement} {
BEGIN [ DEFERRED | IMMEDIATE | EXCLUSIVE ] [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
END [TRANSACTION [<name>]]
................................................................................
}
Syntax {sql-statement} {
COMMIT [TRANSACTION [<name>]]
}
Syntax {sql-statement} {
ROLLBACK [TRANSACTION [<name>]]
}
</tcl>


<p>
No changes can be made to the database except within a transaction.
Any command that changes the database (basically, any SQL command
other than SELECT) will automatically start a transaction if
one is not already in effect.  Automatically started transactions
are committed at the conclusion of the command.
................................................................................
error, but no harm is caused by this.</p>

<p>Future versions of SQLite may extend the list of errors which
might cause automatic transaction rollback.  Future versions of
SQLite might change the error response.  In particular, we may
choose to simplify the interface in future versions of SQLite by
causing the errors above to force an unconditional rollback.</p>



<tcl>
###############################################################################
Section comment comment

Syntax {comment} {<SQL-comment> | <C-comment>
} {SQL-comment} {-- <single-line>
} {C-comment} {/STAR <multiple-lines> [STAR/]
}
</tcl>


<p> Comments aren't SQL commands, but can occur in SQL queries. They are 
treated as whitespace by the parser.  They can begin anywhere whitespace 
can be found, including inside expressions that span multiple lines.
</p>

<p> SQL comments only extend to the end of the current line.</p>

................................................................................
<p> C comments can span any number of lines.  If there is no terminating
delimiter, they extend to the end of the input.  This is not treated as
an error.  A new SQL statement can begin on a line after a multiline
comment ends.  C comments can be embedded anywhere whitespace can occur,
including inside expressions, and in the middle of other SQL statements.
C comments do not nest.  SQL comments inside a C comment will be ignored.
</p>



















































<tcl>
##############################################################################
Section {CREATE INDEX} createindex

Syntax {sql-statement} {
CREATE [UNIQUE] INDEX [IF NOT EXISTS] [<database-name> .] <index-name> 
ON <table-name> ( <column-name> [, <column-name>]* )
} {column-name} {
<name> [ COLLATE <collation-name>] [ ASC | DESC ]
}
</tcl>


<p>The CREATE INDEX command consists of the keywords "CREATE INDEX" followed
by the name of the new index, the keyword "ON", the name of a previously
created table that is to be indexed, and a parenthesized list of names of
columns in the table that are used for the index key.
Each column name can be followed by one of the "ASC" or "DESC" keywords
to indicate sort order, but the sort order is ignored in the current
implementation.  Sorting is always done in ascending order.</p>
................................................................................
SQLite's internal representation of the index layout.</p>

<p>If the optional IF NOT EXISTS clause is present and another index
with the same name aleady exists, then this command becomes a no-op.</p>

<p>Indexes are removed with the <a href="#dropindex">DROP INDEX</a> 
command.</p>



<tcl>
##############################################################################
Section {CREATE TABLE} {createtable}

Syntax {sql-command} {
CREATE [TEMP | TEMPORARY] TABLE [IF NOT EXISTS] [<database-name> .] <table-name> (
  <column-def> [, <column-def>]*
  [, <constraint>]*
)
................................................................................
} {constraint} {
PRIMARY KEY ( <column-list> ) [ <conflict-clause> ] |
UNIQUE ( <column-list> ) [ <conflict-clause> ] |
CHECK ( <expr> )
} {conflict-clause} {
ON CONFLICT <conflict-algorithm>
}
</tcl>


<p>A CREATE TABLE statement is basically the keywords "CREATE TABLE"
followed by the name of a new table and a parenthesized list of column
definitions and constraints.  The table name can be either an identifier
or a string.  Tables names that begin with "<b>sqlite_</b>" are reserved
for use by the engine.</p>

<p>Each column definition is the name of the column followed by the
................................................................................
that has datatype INTEGER, then that column is used internally
as the actual key of the B-Tree for the table.  This means that the column
may only hold unique integer values.  (Except for this one case,
SQLite ignores the datatype specification of columns and allows
any kind of data to be put in a column regardless of its declared
datatype.)  If a table does not have an INTEGER PRIMARY KEY column,
then the B-Tree key will be a automatically generated integer.
<a name="rowid"></a> The
B-Tree key for a row can always be accessed using one of the
special names "<b>ROWID</b>", "<b>OID</b>", or "<b>_ROWID_</b>".
This is true regardless of whether or not there is an INTEGER
PRIMARY KEY.  An INTEGER PRIMARY KEY column can also include the
keyword AUTOINCREMENT.  The AUTOINCREMENT keyword modified the way
that B-Tree keys are automatically generated.  Additional detail
on automatic B-Tree key generation is available
................................................................................
</p>

<p>If the optional IF NOT EXISTS clause is present and another table
with the same name aleady exists, then this command becomes a no-op.</p>

<p>Tables are removed using the <a href="#droptable">DROP TABLE</a> 
statement.  </p>



<tcl>
##############################################################################
Section {CREATE TRIGGER} createtrigger

Syntax {sql-statement} {
CREATE [TEMP | TEMPORARY] TRIGGER [IF NOT EXISTS] <trigger-name> [ BEFORE | AFTER ]
<database-event> ON [<database-name> .] <table-name>
<trigger-action>
}
................................................................................
END
}

Syntax {trigger-step} {
<update-statement> | <insert-statement> | 
<delete-statement> | <select-statement> 
}
</tcl>


<p>The CREATE TRIGGER statement is used to add triggers to the 
database schema. Triggers are database operations (the <i>trigger-action</i>) 
that are automatically performed when a specified database event (the
<i>database-event</i>) occurs.  </p>

<p>A trigger may be specified to fire whenever a DELETE, INSERT or UPDATE of a
particular database table occurs, or whenever an UPDATE of one or more
................................................................................

<p><b>Example:</b></p>

<p>Assuming that customer records are stored in the "customers" table, and
that order records are stored in the "orders" table, the following trigger
ensures that all associated orders are redirected when a customer changes
his or her address:</p>

<tcl>Example {
CREATE TRIGGER update_customer_address UPDATE OF address ON customers 
  BEGIN
    UPDATE orders SET address = new.address WHERE customer_name = old.name;
  END;
}</tcl>


<p>With this trigger installed, executing the statement:</p>


<tcl>Example {
UPDATE customers SET address = '1 Main St.' WHERE name = 'Jack Jones';
}</tcl>


<p>causes the following to be automatically executed:</p>

<tcl>Example {
UPDATE orders SET address = '1 Main St.' WHERE customer_name = 'Jack Jones';
}</tcl>



<p>Note that currently, triggers may behave oddly when created on tables
  with INTEGER PRIMARY KEY fields. If a BEFORE trigger program modifies the 
  INTEGER PRIMARY KEY field of a row that will be subsequently updated by the
  statement that causes the trigger to fire, then the update may not occur. 
  The workaround is to declare the table with a PRIMARY KEY column instead
  of an INTEGER PRIMARY KEY column.</p>



<p>A special SQL function RAISE() may be used within a trigger-program, with the following syntax</p> 

<tcl>
###############################################################################
Syntax {raise-function} {
RAISE ( ABORT, <error-message> ) | 
RAISE ( FAIL, <error-message> ) | 
RAISE ( ROLLBACK, <error-message> ) | 
RAISE ( IGNORE )
}
</tcl>

<p>When one of the first three forms is called during trigger-program execution, the specified ON CONFLICT processing is performed (either ABORT, FAIL or 
 ROLLBACK) and the current query terminates. An error code of SQLITE_CONSTRAINT is returned to the user, along with the specified error message.</p>

<p>When RAISE(IGNORE) is called, the remainder of the current trigger program,
the statement that caused the trigger program to execute and any subsequent
    trigger programs that would of been executed are abandoned. No database
    changes are rolled back.  If the statement that caused the trigger program
    to execute is itself part of a trigger program, then that trigger program
    resumes execution at the beginning of the next step.
</p>

<p>Triggers are removed using the <a href="#droptrigger">DROP TRIGGER</a>
statement.</p>



<tcl>
###############################################################################
Section {CREATE VIEW} {createview}

Syntax {sql-command} {
CREATE [TEMP | TEMPORARY] VIEW [IF NOT EXISTS] [<database-name>.] <view-name> AS <select-statement>
}
</tcl>


<p>The CREATE VIEW command assigns a name to a pre-packaged 
<a href="#select">SELECT</a>
statement.  Once the view is created, it can be used in the FROM clause
of another SELECT in place of a table name.
</p>

<p>If the "TEMP" or "TEMPORARY" keyword occurs in between "CREATE"
................................................................................
the table is created in the main database.</p>

<p>You cannot COPY, DELETE, INSERT or UPDATE a view.  Views are read-only 
in SQLite.  However, in many cases you can use a <a href="#createtrigger">
TRIGGER</a> on the view to accomplish the same thing.  Views are removed 
with the <a href="#dropview">DROP VIEW</a> 
command.</p>


<tcl>
##############################################################################
Section {CREATE VIRTUAL TABLE} {createvtab}

Syntax {sql-command} {
CREATE VIRTUAL TABLE [<database-name> .] <table-name> USING <module-name> [( <arguments> )]
}
</tcl>


<p>A virtual table is an interface to an external storage or computation
engine that appears to be a table but does not actually store information
in the database file.</p>

<p>In general, you can do anything with a virtual table that can be done
with an ordinary table, except that you cannot create triggers on a
virtual table.  Some virtual table implementations might impose additional
................................................................................
SQLite passes the module arguments directly
to the module without any interpretation.  It is the responsibility
of the module implementation to parse and interpret its own arguments.</p>

<p>A virtual table is destroyed using the ordinary
<a href="#droptable">DROP TABLE</a> statement.  There is no
DROP VIRTUAL TABLE statement.</p>


<tcl>
##############################################################################
Section DELETE delete

Syntax {sql-statement} {
DELETE FROM [<database-name> .] <table-name> [WHERE <expr>]
}
</tcl>


<p>The DELETE command is used to remove records from a table.
The command consists of the "DELETE FROM" keywords followed by
the name of the table from which records are to be removed.
</p>

<p>Without a WHERE clause, all rows of the table are removed.
If a WHERE clause is supplied, then only those rows that match
the expression are removed.</p>



<tcl>
###############################################################################
Section {DETACH DATABASE} detach

Syntax {sql-command} {
DETACH [DATABASE] <database-name>
}
</tcl>


<p>This statement detaches an additional database connection previously 
attached using the <a href="#attach">ATTACH DATABASE</a> statement.  It
is possible to have the same database file attached multiple times using 
different names, and detaching one connection to a file will leave the 
others intact.</p>

<p>This statement will fail if SQLite is in the middle of a transaction.</p>



<tcl>
##############################################################################
Section {DROP INDEX} dropindex

Syntax {sql-command} {
DROP INDEX [IF EXISTS] [<database-name> .] <index-name>
}
</tcl>


<p>The DROP INDEX statement removes an index added
with the <a href="#createindex">
CREATE INDEX</a> statement.  The index named is completely removed from
the disk.  The only way to recover the index is to reenter the
appropriate CREATE INDEX command.</p>

<p>The DROP INDEX statement does not reduce the size of the database 
file in the default mode.
Empty space in the database is retained for later INSERTs.  To 
remove free space in the database, use the <a href="#vacuum">VACUUM</a> 
command.  If AUTOVACUUM mode is enabled for a database then space
will be freed automatically by DROP INDEX.</p>



<tcl>
##############################################################################
Section {DROP TABLE} droptable

Syntax {sql-command} {
DROP TABLE [IF EXISTS] [<database-name>.] <table-name>
}
</tcl>


<p>The DROP TABLE statement removes a table added with the <a href=
"#createtable">CREATE TABLE</a> statement.  The name specified is the
table name.  It is completely removed from the database schema and the 
disk file.  The table can not be recovered.  All indices associated 
with the table are also deleted.</p>

<p>The DROP TABLE statement does not reduce the size of the database 
................................................................................
later INSERTs.  To 
remove free space in the database, use the <a href="#vacuum">VACUUM</a> 
command.  If AUTOVACUUM mode is enabled for a database then space
will be freed automatically by DROP TABLE.</p>

<p>The optional IF EXISTS clause suppresses the error that would normally
result if the table does not exist.</p>



<tcl>
##############################################################################
Section {DROP TRIGGER} droptrigger
Syntax {sql-statement} {
DROP TRIGGER [IF EXISTS] [<database-name> .] <trigger-name>
}
</tcl>

<p>The DROP TRIGGER statement removes a trigger created by the 
<a href="#createtrigger">CREATE TRIGGER</a> statement.  The trigger is 
deleted from the database schema. Note that triggers are automatically 
dropped when the associated table is dropped.</p>



<tcl>
##############################################################################
Section {DROP VIEW} dropview

Syntax {sql-command} {
DROP VIEW [IF EXISTS] <view-name>
}
</tcl>


<p>The DROP VIEW statement removes a view created by the <a href=
"#createview">CREATE VIEW</a> statement.  The name specified is the 
view name.  It is removed from the database schema, but no actual data 
in the underlying base tables is modified.</p>



<tcl>
##############################################################################
Section EXPLAIN explain

Syntax {sql-statement} {
EXPLAIN <sql-statement>
}
</tcl>


<p>The EXPLAIN command modifier is a non-standard extension.  The
idea comes from a similar command found in PostgreSQL, but the operation
is completely different.</p>

<p>If the EXPLAIN keyword appears before any other SQLite SQL command
then instead of actually executing the command, the SQLite library will
report back the sequence of virtual machine instructions it would have
used to execute the command had the EXPLAIN keyword not been present.
For additional information about virtual machine instructions see
the <a href="arch.html">architecture description</a> or the documentation
on <a href="opcode.html">available opcodes</a> for the virtual machine.</p>



<tcl>
##############################################################################
Section expression expr

Syntax {expr} {
<expr> <binary-op> <expr> |
<expr> [NOT] <like-op> <expr> [ESCAPE <expr>] |
<unary-op> <expr> |
( <expr> ) |
................................................................................
[EXISTS] ( <select-statement> ) |
CASE [<expr>] LP WHEN <expr> THEN <expr> RPPLUS [ELSE <expr>] END |
CAST ( <expr> AS <type> ) |
<expr> COLLATE <collation-name>
} {like-op} {
LIKE | GLOB | REGEXP | MATCH
}
</tcl>


<p>This section is different from the others.  Most other sections of
this document talks about a particular SQL command.  This section does
not talk about a standalone command but about "expressions" which are 
subcomponents of most other commands.</p>

<p>SQLite understands the following binary operators, in order from
highest to lowest precedence:</p>
................................................................................
any binary operator.</p>

<p>The unary operator [Operator +] is a no-op.  It can be applied
to strings, numbers, or blobs and it always gives as its result the
value of the operand.</p>

<p>Note that there are two variations of the equals and not equals
operators.  Equals can be either

<tcl>
puts "[Operator =] or [Operator ==].
The non-equals operator can be either
[Operator !=] or [Operator {&lt;&gt;}].
The [Operator ||] operator is \"concatenate\" - it joins together
the two strings of its operands.
The operator [Operator %] outputs the remainder of its left 
operand modulo its right operand.</p>

<p>The result of any binary operator is a numeric value, except
for the [Operator ||] concatenation operator which gives a string
result.</p>"</tcl>



<a name="literal_value"></a>
<p>
A literal value is an integer number or a floating point number.
Scientific notation is supported.  The "." character is always used
as the decimal point even if the locale setting specifies "," for
this role - the use of "," for the decimal point would result in
................................................................................
<a href="capi3ref.html#sqlite3_bind_int">sqlite3_bind</a> are treated
as NULL.</p>

<a name="like"></a>
<p>The LIKE operator does a pattern matching comparison. The operand
to the right contains the pattern, the left hand operand contains the
string to match against the pattern. 

<tcl>puts "A percent symbol [Operator %] in the pattern matches any
sequence of zero or more characters in the string.  An underscore
[Operator _] in the pattern matches any single character in the
string.  Any other character matches itself or it's lower/upper case
equivalent (i.e. case-insensitive matching).  (A bug: SQLite only
understands upper/lower case for 7-bit Latin characters.  Hence the
LIKE operator is case sensitive for 8-bit iso8859 characters or UTF-8
characters.  For example, the expression <b>'a'&nbsp;LIKE&nbsp;'A'</b>
is TRUE but <b>'&aelig;'&nbsp;LIKE&nbsp;'&AElig;'</b> is FALSE.).</p>"</tcl>


<p>If the optional ESCAPE clause is present, then the expression
following the ESCAPE keyword must evaluate to a string consisting of
a single character. This character may be used in the LIKE pattern
to include literal percent or underscore characters. The escape
character followed by a percent symbol, underscore or itself matches a
literal percent symbol, underscore or escape character in the string,
respectively. The infix LIKE operator is implemented by calling the
user function <a href="#likeFunc"> like(<i>X</i>,<i>Y</i>)</a>.</p>



The LIKE operator is not case sensitive and will match upper case
characters on one side against lower case characters on the other.  
(A bug: SQLite only understands upper/lower case for 7-bit Latin
characters.  Hence the LIKE operator is case sensitive for 8-bit
iso8859 characters or UTF-8 characters.  For example, the expression
<b>'a'&nbsp;LIKE&nbsp;'A'</b> is TRUE but
<b>'&aelig;'&nbsp;LIKE&nbsp;'&AElig;'</b> is FALSE.).</p>
................................................................................
<td valign="top">Return a copy of the first non-NULL argument.  If
both arguments are NULL then NULL is returned. This behaves the same as 
<b>coalesce()</b> above.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="hexFunc"></a>
hex(<i>X</i>)</td>
<td valign="top">The argument is interpreted as a BLOB.  The result
is a hexadecimal rendering of the content of that blob.</td>
</tr>

<tr>
<td valign="top" align="right">last_insert_rowid()</td>
................................................................................
converted to lower case.  The C library <b>tolower()</b> routine is used
for the conversion, which means that this function might not
work correctly on UTF-8 characters.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="ltrimFunc"></a>
ltrim(<i>X</i>)<br>ltrim(<i>X</i>,<i>Y</i>)</td>
<td valign="top">Return a string formed by removing any and all
characters that appear in <i>Y</i> from the left side of <i>X</i>.
If the <i>Y</i> argument is omitted, spaces are removed.</td>
</tr>


................................................................................
<td valign="top" align="right">random(*)</td>
<td valign="top">Return a pseudo-random integer
between -9223372036854775808 and +9223372036854775807.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="replaceFunc"></a>
replace(<i>X</i>,<i>Y</i>,<i>Z</i>)</td>
<td valign="top">Return a string formed by substituting string <i>Z</i> for
every occurrance of string <i>Y</i> in string <i>X</i>.  The BINARY
collating sequence is used for comparisons.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="randomblobFunc"></a>
randomblob(<i>N</i>)</td>
<td valign="top">Return a <i>N</i>-byte blob containing pseudo-random bytes.
<i>N</i> should be a postive integer.</td>
</tr>

<tr>
<td valign="top" align="right">round(<i>X</i>)<br>round(<i>X</i>,<i>Y</i>)</td>
................................................................................
<td valign="top">Round off the number <i>X</i> to <i>Y</i> digits to the
right of the decimal point.  If the <i>Y</i> argument is omitted, 0 is 
assumed.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="rtrimFunc"></a>
rtrim(<i>X</i>)<br>rtrim(<i>X</i>,<i>Y</i>)</td>
<td valign="top">Return a string formed by removing any and all
characters that appear in <i>Y</i> from the right side of <i>X</i>.
If the <i>Y</i> argument is omitted, spaces are removed.</td>
</tr>

<tr>
................................................................................
right rather than the left.  If <i>X</i> is string
then characters indices refer to actual UTF-8 characters.  If
<i>X</i> is a BLOB then the indices refer to bytes.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="trimFunc"></a>
trim(<i>X</i>)<br>trim(<i>X</i>,<i>Y</i>)</td>
<td valign="top">Return a string formed by removing any and all
characters that appear in <i>Y</i> from both ends of <i>X</i>.
If the <i>Y</i> argument is omitted, spaces are removed.</td>
</tr>


................................................................................
upper-case letters.  The implementation of this function uses the C library
routine <b>toupper()</b> which means it may not work correctly on 
UTF-8 strings.</td>
</tr>

<tr>
<td valign="top" align="right">zeroblob(<i>N</i>)</td>
<td valign="top"><a name="zeroblob"></a>
Return a BLOB consisting of N bytes of 0x00.  SQLite
manages these zeroblobs very efficiently.  Zeroblobs can be used to
reserve space for a BLOB that is later written using 
<a href="capi3ref.html#sqlite3_blob_open">incremental BLOB I/O</a>.</td>
</tr>

</table>
................................................................................

   <p>Sum() will throw an "integer overflow" exception if all inputs
   are integers or NULL
   and an integer overflow occurs at any point during the computation.
   Total() never throws an exception.</p>
</tr>
</table>



<tcl>
##############################################################################
Section INSERT insert

Syntax {sql-statement} {
INSERT [OR <conflict-algorithm>] INTO [<database-name> .] <table-name> [(<column-list>)] VALUES(<value-list>) |
INSERT [OR <conflict-algorithm>] INTO [<database-name> .] <table-name> [(<column-list>)] <select-statement>
}
</tcl>


<p>The INSERT statement comes in two basic forms.  The first form
(with the "VALUES" keyword) creates a single new row in an existing table.
If no column-list is specified then the number of values must
be the same as the number of columns in the table.  If a column-list
is specified, then the number of values must match the number of
specified columns.  Columns of the table that do not appear in the
column list are filled with the default value, or with NULL if no
................................................................................
<p>The optional conflict-clause allows the specification of an alternative
constraint conflict resolution algorithm to use during this one command.
See the section titled
<a href="#conflict">ON CONFLICT</a> for additional information.
For compatibility with MySQL, the parser allows the use of the
single keyword <a href="#replace">REPLACE</a> as an alias for "INSERT OR REPLACE".
</p>



<tcl>
##############################################################################
Section {ON CONFLICT clause} conflict

Syntax {conflict-clause} {
ON CONFLICT <conflict-algorithm>
} {conflict-algorithm} {
ROLLBACK | ABORT | FAIL | IGNORE | REPLACE
}
</tcl>


<p>The ON CONFLICT clause is not a separate SQL command.  It is a
non-standard clause that can appear in many other SQL commands.
It is given its own section in this document because it is not
part of standard SQL and therefore might not be familiar.</p>

<p>The syntax for the ON CONFLICT clause is as shown above for
the CREATE TABLE command.  For the INSERT and
................................................................................
satisfy a constraint, it does not invoke delete triggers on those
rows.  This behavior might change in a future release.</p>
</dl>

<p>The algorithm specified in the OR clause of a INSERT or UPDATE
overrides any algorithm specified in a CREATE TABLE.
If no algorithm is specified anywhere, the ABORT algorithm is used.</p>


<tcl>
##############################################################################
Section REINDEX reindex

Syntax {sql-statement} {
  REINDEX <collation name>
}
Syntax {sql-statement} {
  REINDEX [<database-name> .] <table/index-name>
}
</tcl>


<p>The REINDEX command is used to delete and recreate indices from scratch.
This is useful when the definition of a collation sequence has changed.
</p>

<p>In the first form, all indices in all attached databases that use the
named collation sequence are recreated. In the second form, if 
<i>[database-name.]table/index-name</i> identifies a table, then all indices
................................................................................
</p>

<p>If no <i>database-name</i> is specified and there exists both a table or
index and a collation sequence of the specified name, then indices associated
with the collation sequence only are reconstructed. This ambiguity may be
dispelled by always specifying a <i>database-name</i> when reindexing a
specific table or index.


<tcl>
###############################################################################
Section REPLACE replace

Syntax {sql-statement} {
REPLACE INTO [<database-name> .] <table-name> [( <column-list> )] VALUES ( <value-list> ) |
REPLACE INTO [<database-name> .] <table-name> [( <column-list> )] <select-statement>
}
</tcl>


<p>The REPLACE command is an alias for the "INSERT OR REPLACE" variant
of the <a href="#insert">INSERT</a> command.  This alias is provided for
compatibility with MySQL.  See the 
<a href="#insert">INSERT</a> command documentation for additional
information.</p>  



<tcl>
###############################################################################
Section SELECT select

Syntax {sql-statement} {
SELECT [ALL | DISTINCT] <result> [FROM <table-list>]
[WHERE <expr>]
[GROUP BY <expr-list>]
[HAVING <expr>]
................................................................................
} {sort-expr-list} {
<expr> [<sort-order>] [, <expr> [<sort-order>]]*
} {sort-order} {
[ COLLATE <collation-name> ] [ ASC | DESC ]
} {compound_op} {
UNION | UNION ALL | INTERSECT | EXCEPT
}
</tcl>


<p>The SELECT statement is used to query the database.  The
result of a SELECT is zero or more rows of data where each row
has a fixed number of columns.  The number of columns in the
result is specified by the expression list in between the
SELECT and FROM keywords.  Any arbitrary expression can be used
as a result.  If a result expression is }
puts "[Operator *] then all columns of all tables are substituted"
................................................................................
operators combine the results of the SELECTs to the right and left into
a single big table.  The difference is that in UNION all result rows
are distinct where in UNION ALL there may be duplicates.
The INTERSECT operator takes the intersection of the results of the
left and right SELECTs.  EXCEPT takes the result of left SELECT after
removing the results of the right SELECT.  When three or more SELECTs
are connected into a compound, they group from left to right.</p>



<tcl>
##############################################################################
Section UPDATE update

Syntax {sql-statement} {
UPDATE [ OR <conflict-algorithm> ] [<database-name> .] <table-name>
SET <assignment> [, <assignment>]*
[WHERE <expr>]
} {assignment} {
<column-name> = <expr>
}
</tcl>


<p>The UPDATE statement is used to change the value of columns in 
selected rows of a table.  Each assignment in an UPDATE specifies
a column name to the left of the equals sign and an arbitrary expression
to the right.  The expressions may use the values of other columns.
All expressions are evaluated before any assignments are made.
A WHERE clause can be used to restrict which rows are updated.</p>

<p>The optional conflict-clause allows the specification of an alternative
constraint conflict resolution algorithm to use during this one command.
See the section titled
<a href="#conflict">ON CONFLICT</a> for additional information.</p>



<tcl>
##############################################################################
Section VACUUM vacuum

Syntax {sql-statement} {
VACUUM
}
</tcl>


<p>The VACUUM command is an SQLite extension modeled after a similar
command found in PostgreSQL.  If VACUUM is invoked with the name of a
table or index then it is suppose to clean up the named table or index.
In version 1.0 of SQLite, the VACUUM command would invoke 
<b>gdbm_reorganize()</b> to clean up the backend database file.</p>

<p>
VACUUM became a no-op when the GDBM backend was removed from
SQLITE in version 2.0.0.
VACUUM was reimplemented in version 2.8.1.

</p>

<p>When an object (table, index, or trigger) is dropped from the 
database, it leaves behind empty space.  This makes the database 
file larger than it needs to be, but can speed up inserts.  In time 
inserts and deletes can leave the database file structure fragmented, 
which slows down disk access to the database contents.
................................................................................
<a href="pragma.html#pragma_auto_vacuum">auto_vacuum pragma</a>.
When auto-vacuum is enabled for a database, large deletes cause
the size of the database file to shrink.  However, auto-vacuum
also causes excess fragmentation of the database file.  And auto-vacuum
does not compact partially filled pages of the database as VACUUM
does.
</p>


<tcl>
#############################################################################
# A list of keywords.  A asterisk occurs after the keyword if it is on
# the fallback list.
#
set keyword_list [lsort {
   ABORT*
   ADD
   AFTER*
................................................................................
   VALUES
   VIEW*
   VIRTUAL*
   WHEN
   WHERE
}]



puts {<DIV class="pdf_section">}
Section {SQLite Keywords} keywords 
puts {</DIV>}
</tcl>


<p>The SQL standard specifies a huge number of keywords which may not
be used as the names of tables, indices, columns, databases, user-defined
functions, collations, virtual table modules, or any other named object.
The list of keywords is so long that few people can remember them all.
For most SQL code, your safest bet is to never use any English language
word as the name of a user-defined object.</p>

................................................................................
The following are the keywords currently recognized by SQLite:
</p>

<blockquote>
<table width="100%" class="pdf_keywords">
<tr>
<td align="left" valign="top" width="20%">


<tcl>
set n [llength $keyword_list]
set nCol 5
set nRow [expr {($n+$nCol-1)/$nCol}]
set i 0
foreach word $keyword_list {
  if {[string index $word end]=="*"} {
    set word [string range $word 0 end-1]
................................................................................
    puts "</td><td valign=\"top\" align=\"left\" width=\"20%\">"
    set i 1
  } else {
    incr i
  }
  puts "<$font>$word</$font><br>"
}
</tcl>

</td></tr></table></blockquote>

<h2>Special names</h2>

<p>The following are not keywords in SQLite, but are used as names of 
system objects.  They can be used as an identifier for a different 
type of object.</p>
................................................................................
  OID<br>
  ROWID<br>
  SQLITE_MASTER<br>
  SQLITE_SEQUENCE<br>
  SQLITE_TEMP_MASTER<br>
  TEMP<br>
</b></blockquote>