SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code to implement the "sqlite" command line
** utility for accessing SQLite databases.
**
** $Id: shell.c,v 1.158 2007/01/08 14:31:36 drh Exp $
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include "sqlite3.h"
#include <ctype.h>

  return rc;
}

/*
** Text of a help message
*/
static char zHelp[] =
  ".bail ON|OFF           Stop after hitting an error.  Default OFF\n"
  ".databases             List names and files of attached databases\n"
  ".dump ?TABLE? ...      Dump the database in an SQL text format\n"
  ".echo ON|OFF           Turn command echo on or off\n"
  ".exit                  Exit this program\n"
  ".explain ON|OFF        Turn output mode suitable for EXPLAIN on or off.\n"
  ".header(s) ON|OFF      Turn display of headers on or off\n"
  ".help                  Show this message\n"

#
# Run this Tcl script to generate the sqlite.html file.
#
set rcsid {$Id: sqlite.tcl,v 1.25 2007/01/08 14:31:36 drh Exp $}
source common.tcl
header {sqlite3: A command-line access program for SQLite databases}
puts {
<h2>sqlite3: A command-line access program for SQLite databases</h2>

<p>The SQLite library includes a simple command-line utility named
<b>sqlite3</b> that allows the user to manually enter and execute SQL
commands against an SQLite database.  This document provides a brief
introduction on how to use <b>sqlite3</b>.

<h3>Getting Started</h3>

<p>To start the <b>sqlite3</b> program, just type "sqlite3" followed by
the name the file that holds the SQLite database.  If the file does
not exist, a new one is created automatically.
The <b>sqlite3</b> program will
then prompt you to enter SQL.  Type in SQL statements (terminated by a
semicolon), press "Enter" and the SQL will be executed.</p>

<p>For example, to create a new SQLite database named "ex1" 
with a single table named "tbl1", you might do this:</p>
}

  regsub -all { } $body {\ } body
  regsub -all \n $body <br>\n body
  puts $body
  puts {</tt></blockquote>}
}

Code {
$ (((sqlite3 ex1)))
SQLite version 3.3.10
Enter ".help" for instructions
sqlite> (((create table tbl1(one varchar(10), two smallint);)))
sqlite> (((insert into tbl1 values('hello!',10);)))
sqlite> (((insert into tbl1 values('goodbye', 20);)))
sqlite> (((select * from tbl1;)))
hello!|10
goodbye|20
sqlite>
}

puts {
<p>You can terminate the sqlite3 program by typing your systems
End-Of-File character (usually a Control-D) or the interrupt
character (usually a Control-C).</p>

<p>Make sure you type a semicolon at the end of each SQL command!
The sqlite3 program looks for a semicolon to know when your SQL command is
complete.  If you omit the semicolon, sqlite3 will give you a
continuation prompt and wait for you to enter more text to be
added to the current SQL command.  This feature allows you to
enter SQL commands that span multiple lines.  For example:</p>
}

Code {
sqlite> (((CREATE TABLE tbl2 ()))

a special table named "sqlite_master".
You can execute "SELECT" statements against the
special sqlite_master table just like any other table
in an SQLite database.  For example:</p>
}

Code {
$ (((sqlite3 ex1)))
SQlite vresion 3.3.10
Enter ".help" for instructions
sqlite> (((select * from sqlite_master;)))
    type = table
    name = tbl1
tbl_name = tbl1
rootpage = 3
     sql = create table tbl1(one varchar(10), two smallint)

The schema for TEMPORARY tables is not stored in the "sqlite_master" table
since TEMPORARY tables are not visible to applications other than the
application that created the table.  The schema for TEMPORARY tables
is stored in another special table named "sqlite_temp_master".  The
"sqlite_temp_master" table is temporary itself.
</p>

<h3>Special commands to sqlite3</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>}

Code {
sqlite> (((.help)))
.bail ON|OFF           Stop after hitting an error.  Default OFF
.databases             List names and files of attached databases
.dump ?TABLE? ...      Dump the database in an SQL text format
.echo ON|OFF           Turn command echo on or off
.exit                  Exit this program
.explain ON|OFF        Turn output mode suitable for EXPLAIN on or off.
.header(s) ON|OFF      Turn display of headers on or off
.help                  Show this message
.import FILE TABLE     Import data from FILE into TABLE
.indices TABLE         Show names of all indices on TABLE
.load FILE ?ENTRY?     Load an extension library
.mode MODE ?TABLE?     Set output mode where MODE is one of:
                         csv      Comma-separated values
                         column   Left-aligned columns.  (See .width)
                         html     HTML <table> code
                         insert   SQL insert statements for TABLE
                         line     One value per line
                         list     Values delimited by .separator string
                         tabs     Tab-separated values
                         tcl      TCL list elements
.nullvalue STRING      Print STRING in place of NULL values
.output FILENAME       Send output to FILENAME
.output stdout         Send output to the screen
.prompt MAIN CONTINUE  Replace the standard prompts
.quit                  Exit this program
.read FILENAME         Execute SQL in FILENAME
.schema ?TABLE?        Show the CREATE statements
.separator STRING      Change separator used by output mode and .import
.show                  Show the current values for various settings
.tables ?PATTERN?      List names of tables matching a LIKE pattern
.timeout MS            Try opening locked tables for MS milliseconds
.width NUM NUM ...     Set column widths for "column" mode
sqlite> 
}

puts {
<h3>Changing Output Formats</h3>

<p>The sqlite3 program is able to show the results of a query
in eight different formats: "csv", "column", "html", "insert",
"line", "tabs", and "tcl".
You can use the ".mode" dot command to switch between these output
formats.</p>

<p>The default output mode is "list".  In
list mode, each record of a query result is written on one line of
output and each column within that record is separated by a specific
separator string.  The default separator is a pipe symbol ("|").

sqlite> (((select * from tbl1;)))
INSERT INTO 'new_table' VALUES('hello',10);
INSERT INTO 'new_table' VALUES('goodbye',20);
sqlite>
}

puts {
<p>The last output mode is "html".  In this mode, sqlite3 writes
the results of the query as an XHTML table.  The beginning
&lt;TABLE&gt; and the ending &lt;/TABLE&gt; are not written, but
all of the intervening &lt;TR&gt;s, &lt;TH&gt;s, and &lt;TD&gt;s
are.  The html output mode is envisioned as being useful for
CGI.</p>
}

puts {
<h3>Writing results to a file</h3>

<p>By default, sqlite3 sends query results to standard output.  You
can change this using the ".output" command.  Just put the name of
an output file as an argument to the .output command and all subsequent
query results will be written to that file.  Use ".output stdout" to
begin writing to standard output again.  For example:</p>}

Code {
sqlite> (((.mode list)))
sqlite> (((.separator |)))
sqlite> (((.output test_file_1.txt)))
sqlite> (((select * from tbl1;)))
sqlite> (((.exit)))
$ (((cat test_file_1.txt)))
hello|10
goodbye|20
$
}

puts {
<h3>Querying the database schema</h3>

<p>The sqlite3 program provides several convenience commands that
are useful for looking at the schema of the database.  There is
nothing that these commands do that cannot be done by some other
means.  These commands are provided purely as a shortcut.</p>

<p>For example, to see a list of the tables in the database, you
can enter ".tables".</p>
}

Code {
sqlite> (((.tables)))
tbl1
tbl2
sqlite>
}

puts {
<p>The ".tables" command is similar to setting list mode then
executing the following query:</p>

<blockquote><pre>
SELECT name FROM sqlite_master 
WHERE type IN ('table','view') AND name NOT LIKE 'sqlite_%'
UNION ALL 
SELECT name FROM sqlite_temp_master 
WHERE type IN ('table','view') 
ORDER BY 1
</pre></blockquote>

<p>In fact, if you look at the source code to the sqlite3 program
(found in the source tree in the file src/shell.c) you'll find
exactly the above query.</p>

<p>The ".indices" command works in a similar way to list all of
the indices for a particular table.  The ".indices" command takes
a single argument which is the name of the table for which the
indices are desired.  Last, but not least, is the ".schema" command.

<p>Or, if you give an argument to ".schema" because you only
want the schema for a single table, the query looks like this:</p>

<blockquote><pre>
SELECT sql FROM
   (SELECT * FROM sqlite_master UNION ALL
    SELECT * FROM sqlite_temp_master)
WHERE type!='meta' AND sql NOT NULL AND name NOT LIKE 'sqlite_%'
ORDER BY substr(type,2,1), name
</pre></blockquote>

<p>
You can supply an argument to the .schema command.  If you do, the
query looks like this:
</p>

<blockquote><pre>
SELECT sql FROM
   (SELECT * FROM sqlite_master UNION ALL
    SELECT * FROM sqlite_temp_master)
WHERE tbl_name LIKE '%s'
  AND type!='meta' AND sql NOT NULL AND name NOT LIKE 'sqlite_%'
ORDER BY substr(type,2,1), name
</pre></blockquote>

<p>The "%s" in the query is replace by your argument.  This allows you
to view the schema for some subset of the database.</p>
}

Code {
sqlite> (((.schema %abc%)))
}

puts {
<p>

}

puts {
<h3>Converting An Entire Database To An ASCII Text File</h3>

<p>Use the ".dump" command to convert the entire contents of a
database into a single ASCII text file.  This file can be converted
back into a database by piping it back into <b>sqlite3</b>.</p>

<p>A good way to make an archival copy of a database is this:</p>
}

Code {
$ (((echo '.dump' | sqlite3 ex1 | gzip -c >ex1.dump.gz)))
}

puts {
<p>This generates a file named <b>ex1.dump.gz</b> that contains everything
you need to reconstruct the database at a later time, or on another
machine.  To reconstruct the database, just type:</p>
}

Code {
$ (((zcat ex1.dump.gz | sqlite3 ex2)))
}

puts {
<p>The text format is pure SQL so you

can also use the .dump command to export an SQLite database
into other popular SQL database engines.  Like this:</p>
}

Code {
$ (((createdb ex2)))


$ (((sqlite3 ex1 .dump | psql ex2)))
















}

puts {
<h3>Other Dot Commands</h3>

<p>The ".explain" dot command can be used to set the output mode
to "column" and to set the column widths to values that are reasonable

12    Delete        0      0                  
13    Goto          0      11                 
14    ListClose     0      0                  
}

puts {

<p>The ".timeout" command sets the amount of time that the <b>sqlite3</b>
program will wait for locks to clear on files it is trying to access
before returning an error.  The default value of the timeout is zero so
that an error is returned immediately if any needed database table or
index is locked.</p>

<p>And finally, we mention the ".exit" command which causes the
sqlite3 program to exit.</p>

<h3>Using sqlite3 in a shell script</h3>

<p>
One way to use sqlite3 in a shell script is to use "echo" or
"cat" to generate a sequence of commands in a file, then invoke sqlite3
while redirecting input from the generated command file.  This
works fine and is appropriate in many circumstances.  But as
an added convenience, sqlite3 allows a single SQL command to be
entered on the command line as a second argument after the
database name.  When the sqlite3 program is launched with two
arguments, the second argument is passed to the SQLite library
for processing, the query results are printed on standard output
in list mode, and the program exits.  This mechanism is designed
to make sqlite3 easy to use in conjunction with programs like
"awk".  For example:</p>}

Code {
$ (((sqlite3 ex1 'select * from tbl1' |)))
> ((( awk '{printf "<tr><td>%s<td>%s\n",$1,$2 }')))
<tr><td>hello<td>10
<tr><td>goodbye<td>20
$
}

puts {
<h3>Ending shell commands</h3>

<p>
SQLite commands are normally terminated by a semicolon.  In the shell 
you can also use the word "GO" (case-insensitive) or a slash character 
"/" on a line by itself to end a command.  These are used by SQL Server 
and Oracle, respectively.  These won't work in <b>sqlite3_exec()</b>, 
because the shell translates these into a semicolon before passing them 
to that function.</p>
}

puts {
<h3>Compiling the sqlite3 program from sources</h3>

<p>
The sqlite3 program is built automatically when you compile the
SQLite library.  Just get a copy of the source tree, run
"configure" and then "make".</p>
}
footer $rcsid