Provided by: libdbix-multistatementdo-perl_1.00009-2_all 
NAME
DBIx::MultiStatementDo - Multiple SQL statements in a single do() call with any DBI driver
VERSION
version 1.00009
SYNOPSIS
use DBI;
use DBIx::MultiStatementDo;
# Multiple SQL statements in a single string
my $sql_code = <<'SQL';
CREATE TABLE parent (a, b, c , d );
CREATE TABLE child (x, y, "w;", "z;z");
/* C-style comment; */
CREATE TRIGGER "check;delete;parent;" BEFORE DELETE ON parent WHEN
EXISTS (SELECT 1 FROM child WHERE old.a = x AND old.b = y)
BEGIN
SELECT RAISE(ABORT, 'constraint failed;'); -- Inlined SQL comment
END;
-- Standalone SQL; comment; w/ semicolons;
INSERT INTO parent (a, b, c, d) VALUES ('pippo;', 'pluto;', NULL, NULL);
SQL
my $dbh = DBI->connect( 'dbi:SQLite:dbname=my.db', '', '' );
my $batch = DBIx::MultiStatementDo->new( dbh => $dbh );
# Multiple SQL statements in a single call
my @results = $batch->do( $sql_code )
or die $batch->dbh->errstr;
print scalar(@results) . ' statements successfully executed!';
# 4 statements successfully executed!
DESCRIPTION
Some DBI drivers don't support the execution of multiple statements in a single "do()"
call. This module tries to overcome such limitation, letting you execute any number of SQL
statements (of any kind, not only DDL statements) in a single batch, with any DBI driver.
Here is how DBIx::MultiStatementDo works: behind the scenes it parses the SQL code, splits
it into the atomic statements it is composed of and executes them one by one. To split the
SQL code SQL::SplitStatement is used, which uses a more sophisticated logic than a raw
"split" on the ";" (semicolon) character: first, various different statement terminator
tokens are recognized, then SQL::SplitStatement is able to correctly handle the presence
of said tokens inside identifiers, values, comments, "BEGIN ... END" blocks (even nested),
dollar-quoted strings, MySQL custom "DELIMITER"s, procedural code etc., as (partially)
exemplified in the "SYNOPSIS" above.
Automatic transactions support is offered by default, so that you'll have the all-or-
nothing behaviour you would probably expect; if you prefer, you can anyway disable it and
manage the transactions yourself.
METHODS
"new"
• "DBIx::MultiStatementDo->new( %options )"
• "DBIx::MultiStatementDo->new( \%options )"
It creates and returns a new DBIx::MultiStatementDo object. It accepts its options either
as an hash or an hashref.
The following options are recognized:
• "dbh"
The database handle object as returned by DBI::connect(). This option is required.
• "rollback"
A Boolean option which enables (when true) or disables (when false) automatic
transactions. It is set to a true value by default.
• "splitter_options"
This is the options hashref which is passed unaltered to "SQL::SplitStatement->new()"
to build the splitter object, which is then internally used by DBIx::MultiStatementDo
to split the given SQL string.
It defaults to "undef", which should be the best value if the given SQL string
contains only standard SQL. If it contains contains also procedural code, you may need
to fine tune this option.
Please refer to SQL::SplitStatement::new() to see the options it takes.
"do"
• "$batch->do( $sql_string | \@sql_statements )"
• "$batch->do( $sql_string | \@sql_statements , \%attr )"
• "$batch->do( $sql_string | \@sql_statements , \%attr, \@bind_values | @bind_values )"
This is the method which actually executes the SQL statements against your db. As its
first (mandatory) argument, it takes an SQL string containing one or more SQL statements.
The SQL string is split into its atomic statements, which are then executed one-by-one, in
the same order they appear in the given string.
The first argument can also be a reference to a list of (already split) statements, in
which case no split is performed and the statements are executed as they appear in the
list. The list can also be a two-elements list, where the first element is the statements
listref as above, and the second is the placeholder numbers listref, exactly as returned
by the SQL::SplitStatement::split_with_placeholders() method.
Analogously to DBI's "do()", it optionally also takes an hashref of attributes (which is
passed unaltered to "$batch->dbh->do()" for each atomic statement), and the bind values,
either as a listref or a flat list (see below for the difference).
In list context, "do" returns a list containing the values returned by the
"$batch->dbh->do()" call on each single atomic statement.
If the "rollback" option has been set (and therefore automatic transactions are enabled),
in case one of the atomic statements fails, all the other succeeding statements executed
so far, if any, are rolled back and the method (immediately) returns an empty list (since
no statements have actually been committed).
If the "rollback" option is set to a false value (and therefore automatic transactions are
disabled), the method immediately returns at the first failing statement as above, but it
does not roll back any prior succeeding statement, and therefore a list containing the
values returned by the statements (successfully) executed so far is returned (and these
statements are actually committed to the db, if "$dbh->{AutoCommit}" is set).
In scalar context it returns, regardless of the value of the "rollback" option, "undef" if
any of the atomic statements failed, or a true value if all of the atomic statements
succeeded.
Note that to activate the automatic transactions you don't have to do anything more than
setting the "rollback" option to a true value (or simply do nothing, as it is the
default): DBIx::MultiStatementDo will automatically (and temporarily, via "local") set
"$dbh->{AutoCommit}" and "$dbh->{RaiseError}" as needed. No other DBI db handle attribute
is ever touched, so that you can for example set "$dbh->{PrintError}" and enjoy its
effects in case of a failing statement.
If you want to disable the automatic transactions and manage them by yourself, you can do
something along this:
my $batch = DBIx::MultiStatementDo->new(
dbh => $dbh,
rollback => 0
);
my @results;
$batch->dbh->{AutoCommit} = 0;
$batch->dbh->{RaiseError} = 1;
eval {
@results = $batch->do( $sql_string );
$batch->dbh->commit;
1
} or eval {
$batch->dbh->rollback
};
Bind Values as a List Reference
The bind values can be passed as a reference to a list of listrefs, each of which contains
the bind values for the atomic statement it corresponds to. The bind values inner lists
must match the corresponding atomic statements as returned by the internal splitter
object, with "undef" (or empty listref) elements where the corresponding atomic statements
have no placeholders.
Here is an example:
# 7 statements (SQLite valid SQL)
my $sql_code = <<'SQL';
CREATE TABLE state (id, name);
INSERT INTO state (id, name) VALUES (?, ?);
CREATE TABLE city (id, name, state_id);
INSERT INTO city (id, name, state_id) VALUES (?, ?, ?);
INSERT INTO city (id, name, state_id) VALUES (?, ?, ?);
DROP TABLE city;
DROP TABLE state
SQL
# Only 5 elements are required in the bind values list
my $bind_values = [
undef , # or []
[ 1, 'Nevada' ] ,
[] , # or undef
[ 1, 'Las Vegas' , 1 ],
[ 2, 'Carson City', 1 ]
];
my $batch = DBIx::MultiStatementDo->new( dbh => $dbh );
my @results = $batch->do( $sql_code, undef, $bind_values )
or die $batch->dbh->errstr;
If the last statements have no placeholders, the corresponding "undef"s don't need to be
present in the bind values list, as shown above. The bind values list can also have more
elements than the number of the atomic statements, in which case the excess elements will
simply be ignored.
Bind Values as a Flat List
This is a much more powerful feature of "do": when it gets the bind values as a flat list,
it automatically assigns them to the corresponding placeholders (no interleaving "undef"s
are necessary in this case).
In other words, you can regard the given SQL code as a single big statement and pass the
bind values exactly as you would do with the ordinary DBI "do" method.
For example, given $sql_code from the example above, you could simply do:
my @bind_values = ( 1, 'Nevada', 1, 'Las Vegas', 1, 2, 'Carson City', 1 );
my @results = $batch->do( $sql_code, undef, @bind_values )
or die $batch->dbh->errstr;
and get exactly the same result.
Difference between Bind Values as a List Reference and as a Flat List
If you want to pass the bind values as a flat list as described above, you must pass the
first parameter to "do" either as a string (so that the internal splitting is performed)
or, if you want to disable the internal splitting, as a reference to the two-elements list
containing both the statements and the placeholder numbers listrefs (as described above in
do).
In other words, you can't pass the bind values as a flat list and pass at the same time
the (already split) statements without the placeholder numbers listref. To do so, you need
to pass the bind values as a list reference instead, otherwise "do" throws an exception.
To summarize, bind values as a flat list is easier to use but it suffers from this subtle
limitation, while bind values as a list reference is a little bit more cumbersome to use,
but it has no limitations and can therefore always be used.
Recognized Placeholders
The recognized placeholders are:
• question mark placeholders, represented by the "?" character;
• dollar sign numbered placeholders, represented by the "$1, $2, ..., $n" strings;
• named parameters, such as ":foo", ":bar", ":baz" etc.
"dbh"
• "$batch->dbh"
• "$batch->dbh( $new_dbh )"
Getter/setter method for the "dbh" option explained above.
"rollback"
• "$batch->rollback"
• "$batch->rollback( $boolean )"
Getter/setter method for the "rollback" option explained above.
"splitter_options"
• "$batch->splitter_options"
• "$batch->splitter_options( \%options )"
Getter/setter method for the "splitter_options" option explained above.
"split" and "split_with_placeholders"
• "$batch->split( $sql_code )"
• "$batch->split_with_placeholders( $sql_code )"
These are the methods used internally to split the given SQL code. They call respectively
"split" and "split_with_placeholders" on a SQL::SplitStatement instance built with the
"splitter_options" described above.
Normally they shouldn't be used directly, but they could be useful if you want to see how
your SQL code has been split.
If you want instead to see how your SQL code will be split, that is before executing "do",
you can use SQL::SplitStatement by yourself:
use SQL::SplitStatement;
my $splitter = SQL::SplitStatement->new( \%splitter_options );
my @statements = $splitter->split( $sql_code );
# Now you can check @statements if you want...
and then you can execute your statements preventing "do" from performing the splitting
again, by passing "\@statements" to it:
my $batch = DBIx::MultiStatementDo->new( dbh => $dbh );
my @results = $batch->do( \@statements ); # This does not perform the splitting again.
Warning! In previous versions, the "split_with_placeholders" (public) method documented
above did not work, so there is the possibility that someone used the (private,
undocumented) "_split_with_placeholders" method instead (which worked correctly). In this
case, please start using the public method (which now works as advertised), since the
private method will be removed in future versions.
LIMITATIONS
Please look at: SQL::SplitStatement LIMITATIONS
DEPENDENCIES
DBIx::MultiStatementDo depends on the following modules:
• SQL::SplitStatement 0.10000 or newer
• Moose
AUTHOR
Emanuele Zeppieri, "<emazep@cpan.org>"
BUGS
No known bugs so far.
Please report any bugs or feature requests to "bug-dbix-MultiStatementDo at rt.cpan.org",
or through the web interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBIx-MultiStatementDo>. I will be
notified, and then you'll automatically be notified of progress on your bug as I make
changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc DBIx::MultiStatementDo
You can also look for information at:
• RT: CPAN's request tracker
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=DBIx-MultiStatementDo>
• AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/DBIx-MultiStatementDo>
• CPAN Ratings
<http://cpanratings.perl.org/d/DBIx-MultiStatementDo>
• Search CPAN
<http://search.cpan.org/dist/DBIx-MultiStatementDo/>
ACKNOWLEDGEMENTS
Matt S Trout, for having suggested a much more suitable name for this module.
SEE ALSO
• SQL::SplitStatement
• DBI
LICENSE AND COPYRIGHT
Copyright 2010-2011 Emanuele Zeppieri.
This program is free software; you can redistribute it and/or modify it under the terms of
either: the GNU General Public License as published by the Free Software Foundation, or
the Artistic License.
See http://dev.perl.org/licenses/ for more information.