Documentation Source Text

<li>Enhance the [PRAGMA cache_spill] statement to accept a 32-bit integer
    parameter which is the threshold below which cache spilling is prohibited.
<li>On unix, if a symlink to a database file is opened, then the corresponding
    journal files are based on the actual filename, not the symlink name.
<li>Added the "--transaction" option to [sqldiff].
<li>Added the [sqlite3_db_cacheflush()] interface.
<li>Added the [sqlite3_strlike()] interface.
<li>When using [memory-mapped I/O] map the database file read-only so that stray pointers
    and/or array overruns in the application cannot accidently modify the database file.
<li>Added the <em>experimental</em> [sqlite3_snapshot_get()], [sqlite3_snapshot_open()],
    and [sqlite3_snapshot_free()] interfaces.  These are subject to change or removal in
    a subsequent release.
<li>Enhance the ['utc' modifier] in the [date and time functions] so that it is a no-op if
    the date/time is known to already be in UTC.  (This is not a compatibility break since
    the behavior has long been documented as "undefined" in that case.)
<li>Added the [json_group_array()] and [json_group_object()] SQL functions in the
    [json] extension.
<li>Many small performance optimizations.
<p><b>Portability enhancements:</b>
<li>Work around a sign-exension bug in the optimizer of the HP C compiler on HP/UX.
    [https://www.sqlite.org/src/fdiff?sbs=1&v1=869c95b0fc73026d&v2=232c242a0ccb3d67|(details)]
<p><b>Enhancements to the [command-line shell]:</b>
<li>Added the ".changes ON|OFF" and ".vfsinfo" [dot-commands].
<li>Translate between MBCS and UTF8 when
    running in [https://en.wikipedia.org/wiki/Cmd.exe|cmd.exe] on Windows.
<p><b>Enhancements to makefiles:</b>
<li>Added the --enable-editline and --enable-static-shell options
    to the various autoconf-generated configure scripts.
<li>Omit all use of "awk" in the makefiles, to make building easier for MSVC users.

<p><b>Important fixes:</b>
<li>Fix inconsistent integer to floating-point comparison operations that
    could result in a corrupt index if the index is created on a table
    column that contains both large integers and floating point values
    of similar magnitude.  Ticket 
    [https://www.sqlite.org/src/tktview?name=38a97a87a6|38a97a87a6].
<li>Fix an infinite-loop in the query planner that could occur on

}</tcl>

<p>Be careful when using the ".save" command as it will overwrite any
preexisting database files having the same name without prompting for
confirmation.  As with the ".open" command, you might want to use a
full pathname with forward-slash directory separators to avoid ambiguity.

<tcl>hd_fragment dotcmd {dot-commands}</tcl>
<h3>Special commands to sqlite3 (dot-commands)</h3>

<p>
Most of the time, sqlite3 just reads lines of input and passes them
on to the SQLite library for execution.
But if an input line begins with a dot ("."), then
that line is intercepted and interpreted by the sqlite3 program itself.
These "dot commands" are typically used to change the output format
of queries, or to execute certain prepackaged query statements.
</p>

<p>
For a listing of the available dot commands, you can enter ".help"
at any time.  For example:
</p>

<tcl>DisplayCode {
sqlite> (((.help)))
.backup ?DB? FILE      Backup DB (default "main") to FILE
.bail on|off           Stop after hitting an error.  Default OFF
.binary on|off         Turn binary output on or off.  Default OFF
.changes on|off        Show number of rows changed by SQL
.clone NEWDB           Clone data into NEWDB from the existing database
.databases             List names and files of attached databases
.dbinfo ?DB?           Show status information about the database
.dump ?TABLE? ...      Dump the database in an SQL text format
                         If TABLE specified, only dump tables matching
                         LIKE pattern TABLE.
.echo on|off           Turn command echo on or off

.system CMD ARGS...    Run CMD ARGS... in a system shell
.tables ?TABLE?        List names of tables
                         If TABLE specified, only list tables matching
                         LIKE pattern TABLE.
.timeout MS            Try opening locked tables for MS milliseconds
.timer on|off          Turn SQL timer on or off
.trace FILE|off        Output each SQL statement as it is run
.vfsinfo ?AUX?         Information about the top-level VFS
.vfsname ?AUX?         Print the name of the VFS stack
.width NUM1 NUM2 ...   Set column widths for "column" mode
                         Negative values right-justify
sqlite> 
}</tcl>

<h3>Rules for "dot-commands"</h3>

  This document describes the SQL language that is understood by
  SQLite.  
}
doc {Pragma commands} {pragma.html} {
  This document describes SQLite performance tuning options and other 
  special purpose database commands.
}
doc {Core SQL Functions} {lang_corefunc.html} {
  General-purpose built-in scalar SQL functions.
}
doc {Aggregate SQL Functions} {lang_aggfunc.html} {
  General-purpose built-in aggregate SQL functions.
}
doc {Date and Time SQL Functions} {lang_datefunc.html} {
  SQL functions for manipulating dates and times.
}
doc {JSON SQL Functions} {json1.html} {
  SQL functions for creating, parsing, and querying JSON content.
}
doc {DataTypes} {datatype3.html} {
  SQLite version 3 introduces the concept of manifest typing, where the
  type of a value is associated with the value itself, not the column that
  it is stored in.
  This page describes data typing for SQLite version 3 in further detail.
}

values. 
A varint is between 1 and 9 bytes in length.  The varint consists of either
zero or more byte which have the high-order bit set followed by a single byte
with the high-order bit clear, or nine bytes, whichever is shorter.
The lower seven bits of each of the first eight bytes and all 8 bits of
the ninth byte are used to reconstruct the 64-bit twos-complement integer.
Varints are big-endian: bits taken from the earlier byte of the varint
are the more significant than bits taken from the later bytes. </p>

<p>The format of a cell depends on which kind of b-tree page the cell
appears on.  The following table shows the elements of a cell, in
order of appearance, for the various b-tree page types.</p>

<blockquote><dl>
<dt><p>Table B-Tree Leaf Cell (header 0x0d):</p></dt>

<title>The JSON1 Extension</title>
<tcl>hd_keywords json1 {the json1 extension} {JSON SQL functions}</tcl>
<h2>The JSON1 Extension</h2>

<p>
The <b>json1</b> extension is a [loadable extension] that
implements thirteen [application-defined SQL functions] and
two [table-valued functions] that are useful for
managing [http://json.org/ | JSON] content stored in an SQLite database.
These are the scalar SQL functions implemented by json1:

<blockquote>
<center><table border=0 cellpadding=5>
<tcl>
set tabcnt 0
proc tabentry {fx desc lnk} {
  global tabcnt

tabentry {json_type(json)<br>json_type(json,path)} {
  Return the type of a JSON string or subcomponent.
} jtype

tabentry {json_valid(json)} {
  Return true (1) if the input text is a valid JSON string
} jvalid
</tcl>
</table></center></blockquote>

<p>There are two aggregate SQL functions:

<blockquote><center><table border=0 cellpadding=5>
<tcl>
tabentry {json_group_array(value)} {
  Return a JSON array composed of all <i>value</i> elements 
  in the aggregation.
} jgrouparray

tabentry {json_group_object(name,value)} {
  Return a JSON object composed of all <i>name</i> and <i>value</i> pairs
  in the aggregation.
} jgroupobject
</tcl>
</table></center></blockquote>

<p>The [table-valued functions] implemented by this routine are:

<blockquote><center><table border=0 cellpadding=5>
<tcl>

<tcl>
jexample \
  {json_valid('{"x":35}')} 1 \
  "json_valid('\173\"x\":35')" 0
</tcl>

<tcl>
hd_fragment jgrouparray {json_group_array SQL function} \
   {json_group_array}
hd_fragment jgroupobject {json_group_object SQL function} \
   {json_group_object}
</tcl>
<h3>3.10 The json_group_array() and json_group_object()
aggregate SQL functions</h3>

<p>The json_group_array(X) function is an 
[Aggregate Functions|aggregate SQL function] that returns a JSON array
comprised of all X values in the aggregation.
Similarly, the json_group_object(NAME,VALUE) function returns a JSON object
comprised of all NAME/VALUE pairs in the aggregation.


<tcl>hd_fragment jeach {json_each table-valued function} {json_each}</tcl>
<tcl>hd_fragment jtree {json_tree table-valued function} {json_tree}</tcl>
<h3>3.11 The json_each() and json_tree() table-valued functions</h3>

<p>The json_each(X) and json_tree(X) [table-valued functions] walk the
JSON value provided as their first argument and return one row for each
element.  The json_each(X) function only walks the immediate children
of the top-level array or object or 
or just the top-level element itself if the top-level
element is a primitive value.

<p>
The "path" column is the path to the array or object container the holds 
the current row, or the path to the current row in the case where the 
iteration starts on a primitive type and thus only provides a single
row of output.

<h4>3.11.1 Examples using json_each() and json_tree()</h4>

<p>Suppose the table "CREATE TABLE user(name,phone)" stores zero or
more phone numbers as a JSON array object in the user.phone field.
To find all users who have any phone number with a 704 area code:

<blockquote><pre>
SELECT DISTINCT user.name

<p>^The maximum parameter number is set at compile-time by
the [SQLITE_MAX_VARIABLE_NUMBER] macro.  ^(An individual [database connection]
D can reduce its maximum parameter number below the compile-time maximum
using the [sqlite3_limit](D, [SQLITE_LIMIT_VARIABLE_NUMBER],...) interface.)^
</p>

<tcl>hd_fragment like LIKE ESCAPE</tcl>
<h3>The LIKE, GLOB, REGEXP, and MATCH operators</h3>
<p>^The LIKE operator does a pattern matching comparison. ^The operand
to the right of the LIKE operator contains the pattern and the left hand
operand contains the string to match against the pattern.

<tcl>hd_puts "^A percent symbol (\"%\") in the LIKE pattern matches any
sequence of zero or more characters in the string.  ^An underscore
(\"_\") in the LIKE pattern matches any single character in the

separate the "unixepoch" modifier from prior DDDDDDDDDD then the
behavior is undefined.
Due to precision limitations imposed by the implementations use
of 64-bit integers, the "unixepoch" modifier only works for
dates between 0000-01-01 00:00:00 and 5352-11-01 10:52:47 (unix times
of -62167219200 through 10675199167).</p>

<tcl>hd_fragment localtime {localtime modifier} {'utc' modifier}</tcl>
<p>^The "localtime" modifier (12) assumes the time string to its left is in
Universal Coordinated Time (UTC) and adjusts the time
string so that it displays localtime.  If "localtime"
follows a time that is not UTC, then the behavior is undefined.
^(The "utc" modifier is the opposite of "localtime".  
"utc" assumes that the string
to its left is in the local timezone and adjusts that string to be in UTC.)^
If the prior string is not in localtime, then the result of "utc" is
undefined.</p>

<h3>Examples</h3>

^(<p>Compute the current date.<p>

<p>
Precise numbers are difficult to obtain and so exact rankings
are impossible.  But our best guess is that SQLite is the second
mostly widely deployed software library, after libz.
Some commentators observe that SQLite tends
to be statically linked and thus have multiple instances on
each machine, whereas libz tends to have just
a single instance per machine in the form of a shared library or DLL.
So even though the number of devices containing libz
may be greater than the number of
devices that contain SQLite, the total number of instances per device
<em>might</em> be higher for SQLite and so SQLite <em>might</em>
be the single most widely deployed and used software component.
</p>