NAME
DBIx::ThinSQL::SQLite - add various functions to SQLite
VERSION
0.0.14 (2015-06-19) Development release.
SYNOPSIS
use DBIx::ThinSQL;
use DBIx::ThinSQL::SQLite
qw/create_functions
create_methods
create_sqlite_sequence/;
my $db = DBIx::ThinSQL->connect('dbi:SQLite:dbname=...');
# Call once only to initialize permanently
create_sqlite_sequence($db);
# Call after every connect to the database
create_functions( $db, qw/ debug create_sequence currval / );
# Call once every program run
create_methods(qw/create_sequence nextval/);
# Then use SQL functions or Perl methods as required
$db->do(q{ SELECT debug('logged via Log::Any->debug'); });
$db->do(q{ SELECT create_sequence('name'); });
$db->do(q{ SELECT nextval('name'); });
$db->create_sequence('othername');
$db->nextval('othername');
DESCRIPTION
DBIx::ThinSQL::SQLite adds various functions to the SQL syntax
understood by SQLite, using the *sqlite_create_function()* and
*sqlite_create_aggregate_function()* methods of DBD::SQLite. It also
adds sequence methods to DBIx::ThinSQL database handles.
The following functions are exported on request:
create_sqlite_sequence( $dbh )
Ensure that the "sqlite_sequence" table exists. This function must
be called on the database (once only - the changes are permanent)
before any of the other sequence related functions or methods will
work.
This function works by creating (and dropping) a table with an
"INTEGER PRIMARY KEY AUTOINCREMENT" definition. If you are using the
sequence support from this module you probably don't want to be
creating your own tables with the autoincrement feature, as it may
clash with this module.
create_functions( $dbh, @functions )
Add @functions to the SQL understood by SQLite for the database
handle $dbh. @functions can be any combination of the following:
debug( @items )
This function called from SQL context logs @items with a
"debug()" call to a Log::Any instance. If the first item of
@items begins with "/^select/i" then that statement will be run
and the result logged using "log_debug" from DBIx::ThinSQL
instead.
warn( @items )
This function called from SQL context logs @items using Perl's
"warn" function. If the first item of @items begins with
"/^select/i" then that statement will be run using the current
handle and the result warned instead.
create_sequence( $name )
Create a sequence in the database with name $name.
nextval( $name ) -> Int
Advance the sequence to its next value and return that value.
currval( $name ) -> Int
Return the current value of the sequence.
If Digest::SHA is installed then the following functions can also be
created.
sha1( $expr, ... ) -> bytes
Calculate the SHA digest of $expr and return it in a 20-byte
binary form. Unfortunately it seems that the underlying SQLite C
sqlite_create_function() provides no way to identify the result
as a blob, so you must always manually cast the result in SQL
like so:
CAST(sha1(SQLITE_EXPRESSION) AS blob)
sha1_hex( $expr, ... ) -> hexidecimal
Calculate the SQLite digest of $expr and return it in a
40-character hexidecimal form.
sha1_base64( $expr, ... ) -> base64
Calculate the SQLite digest of $expr and return it in a base64
encoded form.
agg_sha1( $expr, $sort_expr ) -> bytes
agg_sha1_hex( $expr, $sort_expr ) -> hexidecimal
agg_sha1_base64( $expr, $sort_expr ) -> base64
These aggregate functions are for use with statements using
GROUP BY. $expr is the expression on which to calculate the SHA1
hash, and $sort_expr determines the (string) comparison order in
which $expr is fed to the SHA1 stream.
Note that user-defined SQLite functions are only valid for the
current session. They must be created each time you connect to the
database. You can have this happen automatically at connect time by
taking advantage of the DBI "Callbacks" attribute:
my $db = DBI::ThinSQL->connect(
$dsn, undef, undef,
{
Callbacks => {
connected => sub {
my $dbh = shift;
create_functions( $dbh,
qw/debug nextval/ );
}
},
}
);
create_methods( @methods )
Add @methods to the DBIx::ThinSQL::db class which can be any
combination of the following:
create_sequence( $name )
Create a sequence in the database with name $name.
nextval( $name ) -> Int
Advance the sequence to its next value and return that value.
currval( $name ) -> Int
Return the current value of the sequence.
These methods are added to a Perl class and are therefore available
to any DBIx::ThinSQL handle.
SEE ALSO
Log::Any
AUTHOR
Mark Lawrence <nomad@null.net>
COPYRIGHT AND LICENSE
Copyright (C) 2013-2014 Mark Lawrence <nomad@null.net>
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.