NAME
    SQL::SplitStatement - Split any SQL code into atomic statements

VERSION
    version 0.20000

SYNOPSIS
        # 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; with semicolons;
        INSERT INTO parent (a, b, c, d) VALUES ('pippo;', 'pluto;', NULL, NULL);
    SQL
    
        use SQL::SplitStatement;
    
        my $sql_splitter = SQL::SplitStatement->new;
        my @statements = $sql_splitter->split($sql_code);
    
        # @statements now is:
        #
        # (
        #     'CREATE TABLE parent(a, b, c   , d    )',
        #     'CREATE TABLE child (x, y, "w;", "z;z")',
        #     '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;\');
        # END',
        #     'INSERT INTO parent (a, b, c, d) VALUES (\'pippo;\', \'pluto;\', NULL, NULL)'
        # )

DESCRIPTION
    This is a simple module which tries to split any SQL code, even
    including non-standard extensions (for the details see the "SUPPORTED
    DBMSs" section below), into the atomic statements it is composed of.

    The logic used to split the SQL code is more sophisticated than a raw
    "split" on the ";" (semicolon) character: first, various different
    statement terminator *tokens* are recognized (see below for the list),
    then this module 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.

    Consider however that this is by no means a validating parser
    (technically speaking, it's just a *context-sensitive tokenizer*). It
    should rather be seen as an in-progress *heuristic* approach, which will
    gradually improve as bugs will be reported. This also means that, with
    the exception of the "LIMITATIONS" detailed below, there are no known
    (to the author) SQL constructs the most current release of this module
    can't handle.

    If your atomic statements are to be fed to a DBMS, you are encouraged to
    use DBIx::MultiStatementDo instead, which uses this module and also
    (optionally) offers automatic transactions support, so that you'll have
    the *all-or-nothing* behavior you would probably want.

METHODS
  "new"
    *   "SQL::SplitStatement->new( %options )"

    *   "SQL::SplitStatement->new( \%options )"

    It creates and returns a new SQL::SplitStatement object. It accepts its
    options either as a hash or a hashref.

    "new" takes the following Boolean options, which all default to false.

    *   "keep_terminators"

        A Boolean option which causes, when set to a false value (which is
        the default), the trailing terminator tokens to be discarded in the
        returned atomic statements. When set to a true value, the
        terminators are kept instead.

        If your statements are to be fed to a DBMS, you are advised to keep
        this option to its default (false) value, since some drivers/DBMSs
        don't want the terminator to be present at the end of the (single)
        statement.

        The strings currently recognized as terminators (depending on the
        *context*) are:

        *   ";" (the *semicolon* character).

        *   "/" (the *forward-slash* character).

        *   A semicolon followed by a forward-slash on its own line. This
            latter string is treated as a single token (it is used to
            terminate PL/SQL procedures).

        *   Any string defined by the MySQL "DELIMITER" command.

        (Note that the last, possibly empty, statement of a given SQL text,
        never has a trailing terminator. See below for an example.)

    *   "keep_terminator"

        An alias for the the "keep_terminators" option explained above. Note
        that if "keep_terminators" and "keep_terminator" are both set at
        object construction time, "new" throws an exception.

    *   "keep_extra_spaces"

        A Boolean option which causes, when set to a false value (which is
        the default), the spaces ("\s") around the statements to be trimmed.
        When set to a true value, these spaces are kept instead.

        When "keep_terminators" is set to false as well, the terminator is
        discarded first (regardless of the spaces around it) and the
        trailing spaces are trimmed then. This ensures that if
        "keep_extra_spaces" is set to false, the returned statements will
        never have trailing (nor leading) spaces, regardless of the
        "keep_terminators" value.

    *   "keep_comments"

        A Boolean option which causes, when set to a false value (which is
        the default), the comments to be discarded in the returned
        statements. When set to a true value, they are kept with the
        statements instead.

        Both SQL and multi-line C-style comments are recognized.

        When kept, each comment is returned in the same string with the
        atomic statement it belongs to. A comment belongs to a statement if
        it appears, in the original SQL code, before the end of that
        statement and after the terminator of the previous statement (if it
        exists), as shown in this pseudo-SQL snippet:

            /* This comment
            will be returned
            together with statement1 */
    
            <statement1>; -- This will go with statement2
                          -- (note the semicolon which closes statement1)
    
            <statement2>
            -- This with statement2 as well

    *   "keep_empty_statements"

        A Boolean option which causes, when set to a false value (which is
        the default), the empty statements to be discarded. When set to a
        true value, the empty statements are returned instead.

        A statement is considered empty when it contains no characters other
        than the terminator and space characters ("\s").

        A statement composed solely of comments is not recognized as empty
        and may therefore be returned even when "keep_empty_statements" is
        false. To avoid this, it is sufficient to leave "keep_comments" to
        false as well.

        Note instead that an empty statement is recognized as such
        regardless of the value of the options "keep_terminators" and
        "keep_extra_spaces".

    These options are basically to be kept to their default (false) values,
    especially if the atomic statements are to be given to a DBMS.

    They are intended mainly for *cosmetic* reasons, or if you want to count
    by how many atomic statements, including the empty ones, your original
    SQL code was composed of.

    Another situation where they are useful (in the general case necessary,
    really), is when you want to retain the ability to verbatim rebuild the
    original SQL string from the returned statements:

        my $verbatim_splitter = SQL::SplitStatement->new(
            keep_terminators      => 1,
            keep_extra_spaces     => 1,
            keep_comments         => 1,
            keep_empty_statements => 1
        );
    
        my @verbatim_statements = $verbatim_splitter->split($sql_string);
    
        $sql_string eq join '', @verbatim_statements; # Always true, given the constructor above.

    Other than this, again, you are highly recommended to stick with the
    defaults.

  "split"
    *   "$sql_splitter->split( $sql_string )"

    This is the method which actually splits the SQL code into its atomic
    components.

    It returns a list containing the atomic statements, in the same order
    they appear in the original SQL code. The atomic statements are returned
    according to the options explained above.

    Note that, as mentioned above, an SQL string which terminates with a
    terminator token (for example a semicolon), contains a trailing empty
    statement: this is correct and it is treated accordingly (if
    "keep_empty_statements" is set to a true value):

        my $sql_splitter = SQL::SplitStatement->new(
            keep_empty_statements => 1
        );
    
        my @statements = $sql_splitter->split( 'SELECT 1;' );
    
        print 'The SQL code contains ' . scalar(@statements) . ' statements.';
        # The SQL code contains 2 statements.

  "split_with_placeholders"
    *   "$sql_splitter->split_with_placeholders( $sql_string )"

    It works exactly as the "split" method explained above, except that it
    returns also a list of integers, each of which is the number of the
    *unnamed placeholders* contained in the corresponding atomic statement.

    More precisely, its return value is a list of two elements, the first of
    which is a reference to the list of the atomic statements exactly as
    returned by the "split" method, while the second is a reference to the
    list of the number of placeholders as explained above.

    Currently the only recognized placeholders are the "?" (question mark)
    characters.

    Here is an example:

        # 4 statements (valid SQLite 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 (?, ?, ?)
    SQL
    
        my $splitter = SQL::SplitStatement->new;
    
        my ( $statements, $placeholders )
            = $splitter->split_with_placeholders( $sql_code );
    
        # $placeholders now is: [0, 2, 0, 3]

    where the returned $placeholders list(ref) is to be read as follows: the
    first statement contains 0 placeholders, the second 2, the third 0 and
    the fourth 3.

  "keep_terminators"
    *   "$sql_splitter->keep_terminator"

    *   "$sql_splitter->keep_terminator( $boolean )"

        Getter/setter method for the "keep_terminator" option explained
        above.

  "keep_terminator"
    An alias for the =head2 "keep_terminators" method explained above.

  "keep_extra_spaces"
    *   "$sql_splitter->keep_extra_spaces"

    *   "$sql_splitter->keep_extra_spaces( $boolean )"

        Getter/setter method for the "keep_extra_spaces" option explained
        above.

  "keep_comments"
    *   "$sql_splitter->keep_comments"

    *   "$sql_splitter->keep_comments( $boolean )"

        Getter/setter method for the "keep_comments" option explained above.

  "keep_empty_statements"
    *   "$sql_splitter->keep_empty_statements"

    *   "$sql_splitter->keep_empty_statements( $boolean )"

        Getter/setter method for the "keep_empty_statements" option
        explained above.

SUPPORTED DBMSs
    SQL::SplitStatement aims to cover the widest possible range of DBMSs,
    SQL dialects and extensions (even proprietary), in a fully transparent
    way for the user.

    Currently it has been tested mainly on SQLite, PostgreSQL, MySQL and
    Oracle.

LIMITATIONS
    To be split correctly, the given SQL code is subject to the following
    limitations, mainly concerning procedural code (the limitation about the
    use of some keywords as unquoted identifiers affecting the previous
    releases, has now been eliminated).

    *   Procedural extensions

        Currently any block of code which start with "DECLARE", "CREATE" or
        "CALL" is correctly recognized, as well as *bare* "BEGIN ... END"
        blocks and *dollar quoted* blocks, therefore a wide range of
        procedural extensions should be handled correctly. However, only
        PL/SQL, PL/PgSQL and MySQL code has been tested so far.

        If you need also other procedural languages to be recognized, please
        let me know (possibly with some test cases).

    *   PL/SQL

        If a *package* contains also an *initialization block*, then it must
        have the package name after the "END" or it must terminate with a
        semicolon and a slash (which is anyway the recommended practice).

        For example, these two package (pseudo-)definitions will be
        correctly split:

            -- OK since it has the trailing slash
            CREATE OR REPLACE PACKAGE BODY my_package_1 AS
                ...
            BEGIN
                ...
            END;
            /
    
            -- OK since it has the package name after the END
            CREATE OR REPLACE PACKAGE BODY my_package_2 AS
                ...
            BEGIN
                ...
            END my_package_2;

        while this one wouldn't, since it contains an initialization block
        and it lacks both the package name after the "END" and the trailing
        slash:

            CREATE OR REPLACE PACKAGE BODY my_package AS
                ...
            BEGIN
                ...
            END;

        Note however that if the initialization block is absent, the package
        block will be correctly recognized even if it lacks both the package
        name after the "END" and the trailing slash.

  Non-limitations
    To be split correctly, the given input must, in general, be
    syntactically valid SQL. For example, an unbalanced "BEGIN" or a
    misspelled keyword could, under certain circumstances, confuse the
    parser and make it trip over the next statement terminator, thus
    returning wrongly split statements. This should not be a problem though,
    as the original (invalid) SQL code would have been unusable anyway
    (remember that this is NOT a validating parser!)

DEPENDENCIES
    SQL::SplitStatement depends on the following modules:

    *   Class::Accessor::Fast

    *   List::MoreUtils

    *   Regexp::Common

    *   SQL::Tokenizer

AUTHOR
    Emanuele Zeppieri, "<emazep@cpan.org>"

BUGS
    No known bugs.

    Please report any bugs or feature requests to "bug-sql-SplitStatement at
    rt.cpan.org", or through the web interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=SQL-SplitStatement>. 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 SQL::SplitStatement

    You can also look for information at:

    *   RT: CPAN's request tracker

        <http://rt.cpan.org/NoAuth/Bugs.html?Dist=SQL-SplitStatement>

    *   AnnoCPAN: Annotated CPAN documentation

        <http://annocpan.org/dist/SQL-SplitStatement>

    *   CPAN Ratings

        <http://cpanratings.perl.org/d/SQL-SplitStatement>

    *   Search CPAN

        <http://search.cpan.org/dist/SQL-SplitStatement/>

ACKNOWLEDGEMENTS
    Igor Sutton for his excellent SQL::Tokenizer, which made writing this
    module a joke.

SEE ALSO
    *   DBIx::MultiStatementDo

    *   sql-split

LICENSE AND COPYRIGHT
    Copyright 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.

