Provided by: libsql-splitstatement-perl_1.00020-1_all 
NAME
SQL::SplitStatement - Split any SQL code into atomic statements
VERSION
version 1.00020
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:
• 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 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.