/ 
SQL-SplitStatement-0.01000
River stage two • 6 direct dependents • 31 total dependents
/ SQL::SplitStatement

NAME

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

VERSION

Version 0.01000

SYNOPSIS

my $sql_code = <<'SQL';
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);
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 very simple module which permits to split any (not only DDL) SQL code 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, so that SQL::SplitStatement is able to correctly handle the presence of the semicolon inside identifiers, values or BEGIN..END blocks (even nested blocks), as exemplified in the synopsis above.

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).

As long as 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) offer 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 as an hashref.

The following options are recognized:

  • keep_semicolon

    A boolean option which causes, when set to a false value (which is the default), the trailing semicolon to be discarded in the returned atomic statements.

    When set to a true value, the trailing semicolons are kept instead.

    If your statements are to be fed to a DBMS, you are strongly encouraged to keep this option to its default (false) value, since some drivers/DBMSs don't accept the semicolon at the end of a statement.

    (Note that the last, possibly empty, statement of a given SQL code, never has a trailing semicolon. 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_semicolon is set to false as well, the semicolon 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_semicolon value.

  • 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 semicolon and space characters (\s).

    Note that this option is completely independent to the others, that is, an empty statement is recognized as such regardless of the values of the above options keep_semicolon 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 intented 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 (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_semicolon        => 1,
    keep_extra_spaces     => 1,
    keep_empty_statements => 1
});

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

$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.

Note that, as mentioned above, an SQL string which terminates with 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.

keep_semicolon

  • $sql_splitter->keep_semicolon

  • $sql_splitter->keep_semicolon( $boolean )

    Getter/setter method for the keep_semicolon 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_empty_statements

  • $sql_splitter->keep_empty_statements

  • $sql_splitter->keep_empty_statements( $boolean )

    Getter/setter method for the keep_empty_statements option explained above.

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.