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SQL-SplitStatement-0.05000
River stage two • 6 direct dependents • 31 total dependents
/ SQL::SplitStatement

NAME

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

VERSION

Version 0.05000

SYNOPSIS

    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 when containing procedural extensions) 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 statement terminator token, so that SQL::SplitStatement is able to correctly handle the presence of said token inside identifiers, values, comments, BEGIN ... END blocks (even nested) and procedural code, as (partially) exemplified in the synopsis above (see also the "LIMITATIONS" section below).

Consider however that this is by no mean a validating parser: it requests its input to be syntactically valid SQL, otherwise it can return unusable statements (that shouldn't be a problem though, as the original SQL code would have been unusable anyway).

If the given SQL code is valid, it is guaranteed however that it will be split correctly (otherwise it is a bug, that will be corrected, once reported).

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 )

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_semicolon

    WARNING! This option (and its getter/set method) is now deprecated and it will be removed in some future version. It has been renamed to: keep_terminator, so please use that instead. Currently any value assigned to keep_semicolon is assigned to keep_terminator.

  • keep_terminator

    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.

    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/DBMS don't want the terminator to be present at the end of the (single) statement.

    The strings currently recognized as terminator tokens 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).

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

  • 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_terminator 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_terminator 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 meta-SQL snippet:

        /* This comment
    will be returned
    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 character 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_terminator 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_terminator       => 1,
        keep_extra_spaces     => 1,
        keep_comments         => 1,
        keep_empty_statements => 1
    );

    my @verbatim_statements = $verbatim_splitter->split($sql_string);

    $sql 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 (aka parameter markers - represented by the ? character) contained in the corresponding atomic statements.

Its return value is a list of two elemnts: the first one is a reference to the list of the atomic statements (exactly as returned by the split method), and the second is a reference to the list of the numbers 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 is [0, 2, 0, 3]

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

keep_terminator

  • $sql_splitter->keep_terminator

  • $sql_splitter->keep_terminator( $boolean )

    Getter/setter method for the keep_terminator option 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.

LIMITATIONS

The only procedural code currently recognized is PL/SQL, that is, blocks of code which start with a DECLARE, a CREATE or anonymous BEGIN ... END blocks.

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

DEPENDENCIES

SQL::SplitStatement depends on the following modules:

AUTHOR

Emanuele Zeppieri, <emazep@cpan.org>

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:

ACKNOWLEDGEMENTS

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

SEE ALSO

LICENSE AND COPYRIGHT

Copyright 2010 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.