sqlite.tcl

sqlite-3.4.1,嵌入式数据库.是一个功能强大的开源数据库,给学习和研发以及小型公司的发展带来了全所未有的好处.

#
# 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>
}

proc Code {body} {
  puts {<blockquote><tt>}
  regsub -all {&} [string trim $body] {\&amp;} body
  regsub -all {>} $body {\&gt;} body
  regsub -all {<} $body {\&lt;} body
  regsub -all {\(\(\(} $body {<b>} body
  regsub -all {\)\)\)} $body {</b>} body
  regsub -all { } $body {\&nbsp;} 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 ()))
   ...> (((  f1 varchar(30) primary key,)))
   ...> (((  f2 text,)))
   ...> (((  f3 real)))
   ...> ((();)))
sqlite> 
}

puts {

<h3>Aside: Querying the SQLITE_MASTER table</h3>

<p>The database schema in an SQLite database is stored in
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)
sqlite>
}

puts {
<p>
But you cannot execute DROP TABLE, UPDATE, INSERT or DELETE against
the sqlite_master table.  The sqlite_master
table is updated automatically as you create or drop tables and
indices from the database.  You can not make manual changes
to the sqlite_master table.
</p>

<p>
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 ("|").
List mode is especially useful when you are going to send the output
of a query to another program (such as AWK) for additional processing.</p>}

Code {
sqlite> (((.mode list)))
sqlite> (((select * from tbl1;)))
hello|10
goodbye|20
sqlite>
}

puts {
<p>You can use the ".separator" dot command to change the separator
for list mode.  For example, to change the separator to a comma and
a space, you could do this:</p>}

Code {
sqlite> (((.separator ", ")))
sqlite> (((select * from tbl1;)))
hello, 10
goodbye, 20
sqlite>
}

puts {
<p>In "line" mode, each column in a row of the database
is shown on a line by itself.  Each line consists of the column
name, an equal sign and the column data.  Successive records are
separated by a blank line.  Here is an example of line mode
output:</p>}

Code {
sqlite> (((.mode line)))
sqlite> (((select * from tbl1;)))
one = hello
two = 10

one = goodbye
two = 20
sqlite>
}

puts {
<p>In column mode, each record is shown on a separate line with the
data aligned in columns.  For example:</p>}

Code {
sqlite> (((.mode column)))
sqlite> (((select * from tbl1;)))
one         two       
----------  ----------
hello       10        
goodbye     20        
sqlite>
}

puts {
<p>By default, each column is at least 10 characters wide. 
Data that is too wide to fit in a column is truncated.  You can
adjust the column widths using the ".width" command.  Like this:</p>}

Code {
sqlite> (((.width 12 6)))
sqlite> (((select * from tbl1;)))
one           two   
------------  ------
hello         10    
goodbye       20    
sqlite>
}

puts {
<p>The ".width" command in the example above sets the width of the first
column to 12 and the width of the second column to 6.  All other column
widths were unaltered.  You can gives as many arguments to ".width" as
necessary to specify the widths of as many columns as are in your
query results.</p>

<p>If you specify a column a width of 0, then the column
width is automatically adjusted to be the maximum of three
numbers: 10, the width of the header, and the width of the
first row of data.  This makes the column width self-adjusting.
The default width setting for every column is this 
auto-adjusting 0 value.</p>

<p>The column labels that appear on the first two lines of output
can be turned on and off using the ".header" dot command.  In the
examples above, the column labels are on.  To turn them off you
could do this:</p>}

Code {
sqlite> (((.header off)))
sqlite> (((select * from tbl1;)))
hello         10    
goodbye       20    
sqlite>
}

puts {
<p>Another useful output mode is "insert".  In insert mode, the output
is formatted to look like SQL INSERT statements.  You can use insert
mode to generate text that can later be used to input data into a 
different database.</p>

<p>When specifying insert mode, you have to give an extra argument
which is the name of the table to be inserted into.  For example:</p>
}

Code {
sqlite> (((.mode insert new_table)))