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.