README

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

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;'); -- Inline 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 test cases will be reported. This also means that,
    except for the "LIMITATIONS" detailed below, there is no known (to the
    author) SQL code the most current release of this module can't correctly
    split.

    The test suite bundled with the distribution (which now includes the
    popular *Sakila* and *Pagila* sample db schemata, as detailed in the
    "SHOWCASE" section below) should give you an idea of the capabilities of
    this module

    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 for documentation
    purposes can be grouped in two sets: "Formatting Options" and "DBMSs
    Specific Options".

   Formatting Options
    *   "keep_terminators"

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

        The possible terminators (which are treated as such depending on the
        context) are:

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

        *   any string defined by the MySQL "DELIMITER" command;

        *   an ";" followed by an "/" (*forward-slash* character) on its own
            line;

        *   an ";" followed by an "." (*dot* character) on its own line,
            followed by an "/" on its own line;

        *   an "/" on its own line regardless of the preceding characters
            (only if the "slash_terminates" option, explained below, is
            set).

        The multi-line terminators above are always treated as a single
        token, that is they are discarded (or returned) as a whole
        (regardless of the "slash_terminates" option value).

        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.

        (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 passed to
        "new", an exception is thrown.

    *   "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 recommended to stick with the defaults.

   DBMSs Specific Options
    The same syntactic structure can have different semantics across
    different SQL dialects, so sometimes it is necessary to help the parser
    to make the right decision. This is the function of these options.

    *   "slash_terminates"

        A Boolean option which causes, when set to a true value (which is
        the default), a "/" (*forward-slash*) on its own line, even without
        a preceding semicolon, to be admitted as a (possible) terminator.

        If set to false, a forward-slash on its own line is treated as a
        statement terminator only if preceded by a semicolon or by a dot and
        a semicolon.

        If you are dealing with Oracle's SQL, you should let this option
        set, since a slash (alone, without a preceding semicolon) is
        sometimes used as a terminator, as it is permitted by SQL*Plus (on
        non-*block* statements).

        With SQL dialects other than Oracle, there is the (theoretical)
        possibility that a slash on its own line can pass the additional
        checks and be considered a terminator (while it shouldn't). This
        chance should be really tiny (it has never been observed in real
        world code indeed). Though negligible, by setting this option to
        false that risk can anyway be ruled out.

  "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
    *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.

    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.

    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.

  "keep_terminators"
    *   "$sql_splitter->keep_terminators"

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

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

  "keep_terminator"
    An alias for the "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.

  "slash_terminates"
    *   "$sql_splitter->slash_terminates"

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

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

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

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

  Procedural Extensions
    Procedural code is by far the most complex to handle.

    Currently any block of code which start with "FUNCTION", "PROCEDURE",
    "DECLARE", "CREATE" or "CALL" is correctly recognized, as well as
    *anonymous* "BEGIN ... END" blocks, *dollar quoted* blocks and blocks
    delimited by a "DELIMITER"-defined *custom terminator*, 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).

LIMITATIONS
    Bound to be plenty, given the heuristic nature of this module (and its
    ambitious goals). However, no limitations are currently known.

    Please report any problematic test case.

  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 non-split statements. This should not be seen as a limitation
    though, as the original (invalid) SQL code would have been unusable
    anyway (remember that this is NOT a validating parser!)

SHOWCASE
    To test the capabilities of this module, you can run it (or rather run
    sql-split) on the files t/data/sakila-schema.sql and
    t/data/pagila-schema.sql included in the distribution, which contain two
    quite large and complex *real world* db schemata, for MySQL and
    PostgreSQL respectively.

    For more information:

    *   Sakila db: <http://dev.mysql.com/doc/sakila/en/sakila.html>

    *   Pagila db: <http://pgfoundry.org/projects/dbsamples>

DEPENDENCIES
    SQL::SplitStatement depends on the following modules:

    *   Carp

    *   Class::Accessor::Fast

    *   List::MoreUtils

    *   Regexp::Common

    *   SQL::Tokenizer 0.22 or newer

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:

    *   AnnoCPAN: Annotated CPAN documentation

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

    *   CPAN Ratings

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

    *   On MetaCPAN

        <https://metacpan.org/pod/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 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.