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add sqlite 3.3.8 to in tree libs
git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3735 d0543943-73ff-0310-b7d9-9358b9ac24b2
This commit is contained in:
Michael Jerris
607
libs/sqlite/www/tclsqlite.tcl
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607
libs/sqlite/www/tclsqlite.tcl
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@@ -0,0 +1,607 @@
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#
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# Run this Tcl script to generate the tclsqlite.html file.
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#
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set rcsid {$Id: tclsqlite.tcl,v 1.16 2006/01/05 15:50:07 drh Exp $}
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source common.tcl
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header {The Tcl interface to the SQLite library}
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proc METHOD {name text} {
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puts "<a name=\"$name\">\n<h3>The \"$name\" method</h3>\n"
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puts $text
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}
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puts {
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<h2>The Tcl interface to the SQLite library</h2>
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<p>The SQLite library is designed to be very easy to use from
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a Tcl or Tcl/Tk script. This document gives an overview of the Tcl
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programming interface.</p>
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<h3>The API</h3>
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<p>The interface to the SQLite library consists of single
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tcl command named <b>sqlite</b> (version 2.8) or <b>sqlite3</b>
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(version 3.0). Because there is only this
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one command, the interface is not placed in a separate
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namespace.</p>
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<p>The <b>sqlite3</b> command is used as follows:</p>
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<blockquote>
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<b>sqlite3</b> <i>dbcmd database-name</i>
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</blockquote>
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<p>
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The <b>sqlite3</b> command opens the database named in the second
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argument. If the database does not already exist, it is
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automatically created.
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The <b>sqlite3</b> command also creates a new Tcl
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command to control the database. The name of the new Tcl command
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is given by the first argument. This approach is similar to the
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way widgets are created in Tk.
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</p>
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<p>
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The name of the database is just the name of a disk file in which
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the database is stored. If the name of the database is an empty
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string or the special name ":memory:" then a new database is created
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in memory.
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</p>
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<p>
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Once an SQLite database is open, it can be controlled using
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methods of the <i>dbcmd</i>. There are currently 21 methods
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defined:</p>
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<p>The <b>sqlite3</b> also accepts an optional third argument called
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the "mode". This argument is a legacy from SQLite version 2 and is
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currently ignored.</p>
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<p>
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<ul>
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}
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foreach m [lsort {
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authorizer
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busy
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cache
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changes
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close
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collate
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collation_needed
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commit_hook
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complete
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copy
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errorcode
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eval
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exists
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function
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last_insert_rowid
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nullvalue
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onecolumn
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progress
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timeout
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total_changes
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trace
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transaction
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}] {
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puts "<li><a href=\"#$m\">$m</a></li>"
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}
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puts {
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</ul>
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</p>
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<p>The use of each of these methods will be explained in the sequel, though
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not in the order shown above.</p>
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}
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##############################################################################
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METHOD eval {
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<p>
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The most useful <i>dbcmd</i> method is "eval". The eval method is used
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to execute SQL on the database. The syntax of the eval method looks
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like this:</p>
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<blockquote>
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<i>dbcmd</i> <b>eval</b> <i>sql</i>
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?<i>array-name </i>? ?<i>script</i>?
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</blockquote>
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<p>
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The job of the eval method is to execute the SQL statement or statements
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given in the second argument. For example, to create a new table in
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a database, you can do this:</p>
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<blockquote>
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<b>sqlite3 db1 ./testdb<br>
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db1 eval {CREATE TABLE t1(a int, b text)}</b>
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</blockquote>
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<p>The above code creates a new table named <b>t1</b> with columns
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<b>a</b> and <b>b</b>. What could be simpler?</p>
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<p>Query results are returned as a list of column values. If a
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query requests 2 columns and there are 3 rows matching the query,
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then the returned list will contain 6 elements. For example:</p>
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<blockquote>
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<b>db1 eval {INSERT INTO t1 VALUES(1,'hello')}<br>
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db1 eval {INSERT INTO t1 VALUES(2,'goodbye')}<br>
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db1 eval {INSERT INTO t1 VALUES(3,'howdy!')}<br>
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set x [db1 eval {SELECT * FROM t1 ORDER BY a}]</b>
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</blockquote>
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<p>The variable <b>$x</b> is set by the above code to</p>
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<blockquote>
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<b>1 hello 2 goodbye 3 howdy!</b>
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</blockquote>
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<p>You can also process the results of a query one row at a time
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by specifying the name of an array variable and a script following
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the SQL code. For each row of the query result, the values of all
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columns will be inserted into the array variable and the script will
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be executed. For instance:</p>
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<blockquote>
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<b>db1 eval {SELECT * FROM t1 ORDER BY a} values {<br>
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parray values<br>
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puts ""<br>
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}</b>
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</blockquote>
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<p>This last code will give the following output:</p>
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<blockquote><b>
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values(*) = a b<br>
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values(a) = 1<br>
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values(b) = hello<p>
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values(*) = a b<br>
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values(a) = 2<br>
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values(b) = goodbye<p>
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values(*) = a b<br>
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values(a) = 3<br>
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values(b) = howdy!</b>
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</blockquote>
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<p>
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For each column in a row of the result, the name of that column
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is used as an index in to array. The value of the column is stored
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in the corresponding array entry. The special array index * is
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used to store a list of column names in the order that they appear.
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</p>
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<p>
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If the array variable name is omitted or is the empty string, then the value of
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each column is stored in a variable with the same name as the column
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itself. For example:
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</p>
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<blockquote>
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<b>db1 eval {SELECT * FROM t1 ORDER BY a} {<br>
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puts "a=$a b=$b"<br>
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}</b>
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</blockquote>
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<p>
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From this we get the following output
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</p>
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<blockquote><b>
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a=1 b=hello<br>
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a=2 b=goodbye<br>
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a=3 b=howdy!</b>
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</blockquote>
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<p>
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Tcl variable names can appear in the SQL statement of the second argument
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in any position where it is legal to put a string or number literal. The
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value of the variable is substituted for the variable name. If the
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variable does not exist a NULL values is used. For example:
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</p>
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<blockquote><b>
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db1 eval {INSERT INTO t1 VALUES(5,$bigblob)}
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</b></blockquote>
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<p>
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Note that it is not necessary to quote the $bigblob value. That happens
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automatically. If $bigblob is a large string or binary object, this
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technique is not only easier to write, it is also much more efficient
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since it avoids making a copy of the content of $bigblob.
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</p>
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}
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##############################################################################
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METHOD close {
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||||
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<p>
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As its name suggests, the "close" method to an SQLite database just
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closes the database. This has the side-effect of deleting the
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||||
<i>dbcmd</i> Tcl command. Here is an example of opening and then
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immediately closing a database:
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</p>
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<blockquote>
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<b>sqlite3 db1 ./testdb<br>
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db1 close</b>
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</blockquote>
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<p>
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If you delete the <i>dbcmd</i> directly, that has the same effect
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as invoking the "close" method. So the following code is equivalent
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to the previous:</p>
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<blockquote>
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<b>sqlite3 db1 ./testdb<br>
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rename db1 {}</b>
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</blockquote>
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}
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##############################################################################
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METHOD transaction {
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<p>
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The "transaction" method is used to execute a TCL script inside an SQLite
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database transaction. The transaction is committed when the script completes,
|
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or it rolls back if the script fails. If the transaction occurs within
|
||||
another transaction (even one that is started manually using BEGIN) it
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is a no-op.
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</p>
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||||
<p>
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The transaction command can be used to group together several SQLite
|
||||
commands in a safe way. You can always start transactions manually using
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BEGIN, of
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course. But if an error occurs so that the COMMIT or ROLLBACK are never
|
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run, then the database will remain locked indefinitely. Also, BEGIN
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does not nest, so you have to make sure no other transactions are active
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before starting a new one. The "transaction" method takes care of
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all of these details automatically.
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</p>
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<p>
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The syntax looks like this:
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</p>
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<blockquote>
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||||
<i>dbcmd</i> <b>transaction</b> <i>?transaction-type?</i>
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<i>SCRIPT,</i>
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||||
</blockquote>
|
||||
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||||
|
||||
<p>
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The <i>transaction-type</i> can be one of <b>deferred</b>,
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<b>exclusive</b> or <b>immediate</b>. The default is deferred.
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</p>
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||||
}
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##############################################################################
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METHOD cache {
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<p>
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The "eval" method described <a href="#eval">above</a> keeps a cache of
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<a href="capi3ref.html#sqlite3_prepare">prepared statements</a>
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for recently evaluated SQL commands.
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||||
The "cache" method is used to control this cache.
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The first form of this command is:</p>
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||||
<blockquote>
|
||||
<i>dbcmd</i> <b>cache size</b> <i>N</i>
|
||||
</blockquote>
|
||||
|
||||
<p>This sets the maximum number of statements that can be cached.
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||||
The upper limit is 100. The default is 10. If you set the cache size
|
||||
to 0, no caching is done.</p>
|
||||
|
||||
<p>The second form of the command is this:</p>
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||||
|
||||
|
||||
<blockquote>
|
||||
<i>dbcmd</i> <b>cache flush</b>
|
||||
</blockquote>
|
||||
|
||||
<p>The cache-flush method
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||||
<a href="capi3ref.html#sqlite3_finalize">finalizes</a>
|
||||
all prepared statements currently
|
||||
in the cache.</p>
|
||||
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD complete {
|
||||
|
||||
<p>
|
||||
The "complete" method takes a string of supposed SQL as its only argument.
|
||||
It returns TRUE if the string is a complete statement of SQL and FALSE if
|
||||
there is more to be entered.</p>
|
||||
|
||||
<p>The "complete" method is useful when building interactive applications
|
||||
in order to know when the user has finished entering a line of SQL code.
|
||||
This is really just an interface to the
|
||||
<a href="capi3ref.html#sqlite3_complete"><b>sqlite3_complete()</b></a> C
|
||||
function.
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD copy {
|
||||
|
||||
<p>
|
||||
The "copy" method copies data from a file into a table.
|
||||
It returns the number of rows processed successfully from the file.
|
||||
The syntax of the copy method looks like this:</p>
|
||||
|
||||
<blockquote>
|
||||
<i>dbcmd</i> <b>copy</b> <i>conflict-algorithm</i>
|
||||
<i>table-name </i> <i>file-name </i>
|
||||
?<i>column-separator </i>?
|
||||
?<i>null-indicator</i>?
|
||||
</blockquote>
|
||||
|
||||
<p>Conflict-alogrithm must be one of the SQLite conflict algorithms for
|
||||
the INSERT statement: <i>rollback</i>, <i>abort</i>,
|
||||
<i>fail</i>,<i>ignore</i>, or <i>replace</i>. See the SQLite Language
|
||||
section for <a href="lang.html#conflict">ON CONFLICT</a> for more information.
|
||||
The conflict-algorithm must be specified in lower case.
|
||||
</p>
|
||||
|
||||
<p>Table-name must already exists as a table. File-name must exist, and
|
||||
each row must contain the same number of columns as defined in the table.
|
||||
If a line in the file contains more or less than the number of columns defined,
|
||||
the copy method rollbacks any inserts, and returns an error.</p>
|
||||
|
||||
<p>Column-separator is an optional column separator string. The default is
|
||||
the ASCII tab character \t. </p>
|
||||
|
||||
<p>Null-indicator is an optional string that indicates a column value is null.
|
||||
The default is an empty string. Note that column-separator and
|
||||
null-indicator are optional positional arguments; if null-indicator
|
||||
is specified, a column-separator argument must be specifed and
|
||||
precede the null-indicator argument.</p>
|
||||
|
||||
<p>The copy method implements similar functionality to the <b>.import</b>
|
||||
SQLite shell command.
|
||||
The SQLite 2.x <a href="lang.html#copy"><b>COPY</b></a> statement
|
||||
(using the PostgreSQL COPY file format)
|
||||
can be implemented with this method as:</p>
|
||||
|
||||
<blockquote>
|
||||
dbcmd copy $conflictalgo
|
||||
$tablename $filename
|
||||
\t
|
||||
\\N
|
||||
</blockquote>
|
||||
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD timeout {
|
||||
|
||||
<p>The "timeout" method is used to control how long the SQLite library
|
||||
will wait for locks to clear before giving up on a database transaction.
|
||||
The default timeout is 0 millisecond. (In other words, the default behavior
|
||||
is not to wait at all.)</p>
|
||||
|
||||
<p>The SQLite database allows multiple simultaneous
|
||||
readers or a single writer but not both. If any process is writing to
|
||||
the database no other process is allows to read or write. If any process
|
||||
is reading the database other processes are allowed to read but not write.
|
||||
The entire database shared a single lock.</p>
|
||||
|
||||
<p>When SQLite tries to open a database and finds that it is locked, it
|
||||
can optionally delay for a short while and try to open the file again.
|
||||
This process repeats until the query times out and SQLite returns a
|
||||
failure. The timeout is adjustable. It is set to 0 by default so that
|
||||
if the database is locked, the SQL statement fails immediately. But you
|
||||
can use the "timeout" method to change the timeout value to a positive
|
||||
number. For example:</p>
|
||||
|
||||
<blockquote><b>db1 timeout 2000</b></blockquote>
|
||||
|
||||
<p>The argument to the timeout method is the maximum number of milliseconds
|
||||
to wait for the lock to clear. So in the example above, the maximum delay
|
||||
would be 2 seconds.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD busy {
|
||||
|
||||
<p>The "busy" method, like "timeout", only comes into play when the
|
||||
database is locked. But the "busy" method gives the programmer much more
|
||||
control over what action to take. The "busy" method specifies a callback
|
||||
Tcl procedure that is invoked whenever SQLite tries to open a locked
|
||||
database. This callback can do whatever is desired. Presumably, the
|
||||
callback will do some other useful work for a short while (such as service
|
||||
GUI events) then return
|
||||
so that the lock can be tried again. The callback procedure should
|
||||
return "0" if it wants SQLite to try again to open the database and
|
||||
should return "1" if it wants SQLite to abandon the current operation.
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD exists {
|
||||
|
||||
<p>The "exists" method is similar to "onecolumn" and "eval" in that
|
||||
it executes SQL statements. The difference is that the "exists" method
|
||||
always returns a boolean value which is TRUE if a query in the SQL
|
||||
statement it executes returns one or more rows and FALSE if the SQL
|
||||
returns an empty set.</p>
|
||||
|
||||
<p>The "exists" method is often used to test for the existance of
|
||||
rows in a table. For example:</p>
|
||||
|
||||
<blockquote><b>
|
||||
if {[db exists {SELECT 1 FROM table1 WHERE user=$user}]} {<br>
|
||||
# Processing if $user exists<br>
|
||||
} else {<br>
|
||||
# Processing if $user does not exist<br>
|
||||
}
|
||||
</b></blockquote>
|
||||
}
|
||||
|
||||
|
||||
##############################################################################
|
||||
METHOD last_insert_rowid {
|
||||
|
||||
<p>The "last_insert_rowid" method returns an integer which is the ROWID
|
||||
of the most recently inserted database row.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD function {
|
||||
|
||||
<p>The "function" method registers new SQL functions with the SQLite engine.
|
||||
The arguments are the name of the new SQL function and a TCL command that
|
||||
implements that function. Arguments to the function are appended to the
|
||||
TCL command before it is invoked.</p>
|
||||
|
||||
<p>
|
||||
The following example creates a new SQL function named "hex" that converts
|
||||
its numeric argument in to a hexadecimal encoded string:
|
||||
</p>
|
||||
|
||||
<blockquote><b>
|
||||
db function hex {format 0x%X}
|
||||
</b></blockquote>
|
||||
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD nullvalue {
|
||||
|
||||
<p>
|
||||
The "nullvalue" method changes the representation for NULL returned
|
||||
as result of the "eval" method.</p>
|
||||
|
||||
<blockquote><b>
|
||||
db1 nullvalue NULL
|
||||
</b></blockquote>
|
||||
|
||||
<p>The "nullvalue" method is useful to differ between NULL and empty
|
||||
column values as Tcl lacks a NULL representation. The default
|
||||
representation for NULL values is an empty string.</p>
|
||||
}
|
||||
|
||||
|
||||
|
||||
##############################################################################
|
||||
METHOD onecolumn {
|
||||
|
||||
<p>The "onecolumn" method works like
|
||||
"<a href="#eval">eval</a>" in that it evaluates the
|
||||
SQL query statement given as its argument. The difference is that
|
||||
"onecolumn" returns a single element which is the first column of the
|
||||
first row of the query result.</p>
|
||||
|
||||
<p>This is a convenience method. It saves the user from having to
|
||||
do a "<tt>[lindex ... 0]</tt>" on the results of an "eval"
|
||||
in order to extract a single column result.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD changes {
|
||||
|
||||
<p>The "changes" method returns an integer which is the number of rows
|
||||
in the database that were inserted, deleted, and/or modified by the most
|
||||
recent "eval" method.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD total_changes {
|
||||
|
||||
<p>The "total_changes" method returns an integer which is the number of rows
|
||||
in the database that were inserted, deleted, and/or modified since the
|
||||
current database connection was first opened.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD authorizer {
|
||||
|
||||
<p>The "authorizer" method provides access to the
|
||||
<a href="capi3ref.html#sqlite3_set_authorizer">sqlite3_set_authorizer</a>
|
||||
C/C++ interface. The argument to authorizer is the name of a procedure that
|
||||
is called when SQL statements are being compiled in order to authorize
|
||||
certain operations. The callback procedure takes 5 arguments which describe
|
||||
the operation being coded. If the callback returns the text string
|
||||
"SQLITE_OK", then the operation is allowed. If it returns "SQLITE_IGNORE",
|
||||
then the operation is silently disabled. If the return is "SQLITE_DENY"
|
||||
then the compilation fails with an error.
|
||||
</p>
|
||||
|
||||
<p>If the argument is an empty string then the authorizer is disabled.
|
||||
If the argument is omitted, then the current authorizer is returned.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD progress {
|
||||
|
||||
<p>This method registers a callback that is invoked periodically during
|
||||
query processing. There are two arguments: the number of SQLite virtual
|
||||
machine opcodes between invocations, and the TCL command to invoke.
|
||||
Setting the progress callback to an empty string disables it.</p>
|
||||
|
||||
<p>The progress callback can be used to display the status of a lengthy
|
||||
query or to process GUI events during a lengthy query.</p>
|
||||
}
|
||||
|
||||
|
||||
##############################################################################
|
||||
METHOD collate {
|
||||
|
||||
<p>This method registers new text collating sequences. There are
|
||||
two arguments: the name of the collating sequence and the name of a
|
||||
TCL procedure that implements a comparison function for the collating
|
||||
sequence.
|
||||
</p>
|
||||
|
||||
<p>For example, the following code implements a collating sequence called
|
||||
"NOCASE" that sorts in text order without regard to case:
|
||||
</p>
|
||||
|
||||
<blockquote><b>
|
||||
proc nocase_compare {a b} {<br>
|
||||
return [string compare [string tolower $a] [string tolower $b]]<br>
|
||||
}<br>
|
||||
db collate NOCASE nocase_compare<br>
|
||||
</b></blockquote>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD collation_needed {
|
||||
|
||||
<p>This method registers a callback routine that is invoked when the SQLite
|
||||
engine needs a particular collating sequence but does not have that
|
||||
collating sequence registered. The callback can register the collating
|
||||
sequence. The callback is invoked with a single parameter which is the
|
||||
name of the needed collating sequence.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD commit_hook {
|
||||
|
||||
<p>This method registers a callback routine that is invoked just before
|
||||
SQLite tries to commit changes to a database. If the callback throws
|
||||
an exception or returns a non-zero result, then the transaction rolls back
|
||||
rather than commit.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD errorcode {
|
||||
|
||||
<p>This method returns the numeric error code that resulted from the most
|
||||
recent SQLite operation.</p>
|
||||
}
|
||||
|
||||
##############################################################################
|
||||
METHOD trace {
|
||||
|
||||
<p>The "trace" method registers a callback that is invoked as each SQL
|
||||
statement is compiled. The text of the SQL is appended as a single string
|
||||
to the command before it is invoked. This can be used (for example) to
|
||||
keep a log of all SQL operations that an application performs.
|
||||
</p>
|
||||
}
|
||||
|
||||
|
||||
footer $rcsid
|
||||
Reference in New Issue
Block a user