phpman > perldoc > SQL::Parser(3pm)

NAME
     SQL::Parser -- validate and parse SQL strings

SYNOPSIS
     use SQL::Parser;                                     # CREATE A PARSER OBJECT
     my $parser = SQL::Parser->new();

     $parser->feature( $class, $name, $value );           # SET OR FIND STATUS OF
     my $has_feature = $parser->feature( $class, $name ); # A PARSER FEATURE

     $parser->dialect( $dialect_name );                   # SET OR FIND STATUS OF
     my $current_dialect = $parser->dialect;              # A PARSER DIALECT

DESCRIPTION
    SQL::Parser is part of the SQL::Statement distribution and, most interaction with the parser
    should be done through SQL::Statement. The methods shown above create and modify a parser
    object. To use the parser object to parse SQL and to examine the resulting structure, you should
    use SQL::Statement.

    Important Note: Previously SQL::Parser had its own hash-based interface for parsing, but that is
    now deprecated and will eventually be phased out in favor of the object-oriented parsing
    interface of SQL::Statement. If you are unable to transition some features to the new interface
    or have concerns about the phase out, please contact me. See "The Parse Structure" for details
    of the now-deprecated hash method if you still need them.

METHODS
  new()
    Create a new parser object

     use SQL::Parser;
     my $parser = SQL::Parser->new();

    The new() method creates a SQL::Parser object which can then be used to parse and validate the
    syntax of SQL strings. It takes two optional parameters - 1) the name of the SQL dialect that
    will define the syntax rules for the parser and 2) a reference to a hash which can contain
    additional attributes of the parser. If no dialect is specified, 'AnyData' is the default.

     use SQL::Parser;
     my $parser = SQL::Parser->new( $dialect_name, \%attrs );

    The dialect_name parameter is a string containing any valid dialect such as 'ANSI', 'AnyData',
    or 'CSV'. See the section on the dialect() method below for details.

    The "attrs" parameter is a reference to a hash that can contain error settings for the
    PrintError and RaiseError attributes.

    An example:

      use SQL::Parser;
      my $parser = SQL::Parser->new('AnyData', {RaiseError=>1} );

      This creates a new parser that uses the grammar rules
      contained in the .../SQL/Dialects/AnyData.pm file and which
      sets the RaiseError attribute to true.

  dialect()
     $parser->dialect( $dialect_name );     # load a dialect configuration file
     my $dialect = $parser->dialect;        # get the name of the current dialect

     For example:

       $parser->dialect('AnyData');  # loads the AnyData config file
       print $parser->dialect;       # prints 'AnyData'

    The $dialect_name parameter may be the name of any dialect configuration file on your system.
    Use the $parser->list('dialects') method to see a list of available dialects. At a minimum it
    will include "ANSI", "CSV", and "AnyData". For backwards compatibility 'Ansi' is accepted as a
    synonym for 'ANSI', otherwise the names are case sensitive.

    Loading a new dialect configuration file erases all current parser features and resets them to
    those defined in the configuration file.

  feature()
    Features define the rules to be used by a specific parser instance. They are divided into the
    following classes:

        * valid_commands
        * valid_options
        * valid_comparison_operators
        * valid_data_types
        * reserved_words

    Within each class a feature name is either enabled or disabled. For example, under
    "valid_data_types" the name "BLOB" may be either disabled or enabled. If it is not enabled
    (either by being specifically disabled, or simply by not being specified at all) then any SQL
    string using "BLOB" as a data type will throw a syntax error "Invalid data type: 'BLOB'".

    The feature() method allows you to enable, disable, or check the status of any feature.

     $parser->feature( $class, $name, 1 );             # enable a feature

     $parser->feature( $class, $name, 0 );             # disable a feature

     my $feature = $parser->feature( $class, $name );  # return status of a feature

     For example:

     $parser->feature('reserved_words','FOO',1);       # make 'FOO' a reserved word

     $parser->feature('valid_data_types','BLOB',0);    # disallow 'BLOB' as a
                                                       # data type

                                                       # determine if the LIKE
                                                       # operator is supported
     my $LIKE = $parser->feature('valid_comparison_operators','LIKE');

    See the section below on "Backwards Compatibility" for use of the feature() method with
    SQL::Statement 0.1x style parameters.

Supported SQL syntax
    The SQL::Statement distribution can be used to either just parse SQL statements or to execute
    them against actual data. A broader set of syntax is supported in the parser than in the
    executor. For example the parser allows you to specify column constraints like PRIMARY KEY.
    Currently, these are ignored by the execution engine. Likewise syntax such as RESTRICT and
    CASCADE on DROP statements or LOCAL GLOBAL TEMPORARY tables in CREATE are supported by the
    parser but ignored by the executor.

    To see the list of Supported SQL syntax formerly kept in this pod, see SQL::Statement.

Subclassing SQL::Parser
    In the event you need to either extend or modify SQL::Parser's default behavior, the following
    methods may be overridden:

    "$self-">"get_btwn($string)"
        Processes the BETWEEN...AND... predicates; default converts to 2 range predicates.

    "$self-">"get_in($string)"
        Process the IN (...list...) predicates; default converts to a series of OR'd '=' predicate,
        or AND'd '<>' predicates for NOT IN.

    "$self-">"transform_syntax($string)"
        Abstract method; default simply returns the original string. Called after repl_btwn() and
        repl_in(), but before any further predicate processing is applied. Possible uses include
        converting other predicate syntax not recognized by SQL::Parser into user-defined functions.

The parse structure
    This section outlines the now-deprecated hash interface to the parsed structure. It is included
    for backwards compatibility only. You should use the SQL::Statement object interface to the
    structure instead. See SQL::Statement.

    Parse Structures

    Here are some further examples of the data structures returned by the structure() method after a
    call to parse(). Only specific details are shown for each SQL instance, not the entire
    structure.

    parse()

    Once a SQL::Parser object has been created with the new() method, the parse() method can be used
    to parse any number of SQL strings. It takes a single required parameter -- a string containing
    a SQL command. The SQL string may optionally be terminated by a semicolon. The parse() method
    returns a true value if the parse is successful and a false value if the parse finds SQL syntax
    errors.

    Examples:

      1) my $success = $parser->parse('SELECT * FROM foo');

      2) my $sql = 'SELECT * FROM foo';
         my $success = $parser->parse( $sql );

      3) my $success = $parser->parse(qq!
             SELECT id,phrase
               FROM foo
              WHERE id < 7
                AND phrase <> 'bar'
           ORDER BY phrase;
       !);

      4) my $success = $parser->parse('SELECT * FRoOM foo ');

    In examples #1,#2, and #3, the value of $success will be true because the strings passed to the
    parse() method are valid SQL strings.

    In example #4, however, the value of $success will be false because the string contains a SQL
    syntax error ('FRoOM' instead of 'FROM').

    In addition to checking the return value of parse() with a variable like $success, you may use
    the PrintError and RaiseError attributes as you would in a DBI script:

     * If PrintError is true, then SQL syntax errors will be sent as
       warnings to STDERR (i.e. to the screen or to a file if STDERR
       has been redirected).  This is set to true by default which
       means that unless you specifically turn it off, all errors
       will be reported.

     * If RaiseError is true, then SQL syntax errors will cause the
       script to die, (i.e. the script will terminate unless wrapped
       in an eval).  This is set to false by default which means
       that unless you specifically turn it on, scripts will
       continue to operate even if there are SQL syntax errors.

    Basically, you should leave PrintError on or else you will not be warned when an error occurs.
    If you are simply validating a series of strings, you will want to leave RaiseError off so that
    the script can check all strings regardless of whether some of them contain SQL errors. However,
    if you are going to try to execute the SQL or need to depend that it is correct, you should set
    RaiseError on so that the program will only continue to operate if all SQL strings use correct
    syntax.

    IMPORTANT NOTE #1: The parse() method only checks syntax, it does NOT verify if the objects
    listed actually exist. For example, given the string "SELECT model FROM cars", the parse()
    method will report that the string contains valid SQL but that will not tell you whether there
    actually is a table called "cars" or whether that table contains a column called 'model'. Those
    kinds of verifications are performed by the SQL::Statement module, not by SQL::Parser by itself.

    IMPORTANT NOTE #2: The parse() method uses rules as defined by the selected dialect
    configuration file and the feature() method. This means that a statement that is valid in one
    dialect may not be valid in another. For example the 'CSV' and 'AnyData' dialects define 'BLOB'
    as a valid data type but the 'ANSI' dialect does not. Therefore the statement 'CREATE TABLE foo
    (picture BLOB)' would be valid in the first two dialects but would produce a syntax error in the
    'ANSI' dialect.

    structure()

    After a SQL::Parser object has been created and the parse() method used to parse a SQL string,
    the structure() method returns the data structure of that string. This data structure may be
    passed on to other modules (e.g. SQL::Statement) or it may be printed out using, for example,
    the Data::Dumper module.

    The data structure contains all of the information in the SQL string as parsed into its various
    components. To take a simple example:

     $parser->parse('SELECT make,model FROM cars');
     use Data::Dumper;
     print Dumper $parser->structure;

    Would produce:

     $VAR1 = {
              'column_defs' => [
                                  { 'type'  => 'column',
                                    'value' => 'make', },
                                  { 'type'  => 'column',
                                    'value' => 'model', },
                                ],
              'command' => 'SELECT',
              'table_names' => [
                                 'cars'
                               ]
            };


     'SELECT make,model, FROM cars'

          command => 'SELECT',
          table_names => [ 'cars' ],
          column_names => [ 'make', 'model' ],

     'CREATE TABLE cars ( id INTEGER, model VARCHAR(40) )'

          column_defs => {
              id    => { data_type => INTEGER     },
              model => { data_type => VARCHAR(40) },
          },

     'SELECT DISTINCT make FROM cars'

          set_quantifier => 'DISTINCT',

     'SELECT MAX (model) FROM cars'

        set_function   => {
            name => 'MAX',
            arg  => 'models',
        },

     'SELECT * FROM cars LIMIT 5,10'

        limit_clause => {
            offset => 5,
            limit  => 10,
        },

     'SELECT * FROM vars ORDER BY make, model DESC'

        sort_spec_list => [
            { make  => 'ASC'  },
            { model => 'DESC' },
        ],

     "INSERT INTO cars VALUES ( 7, 'Chevy', 'Impala' )"

        values => [ 7, 'Chevy', 'Impala' ],

SUPPORT
    You can find documentation for this module with the perldoc command.

        perldoc SQL::Parser
        perldoc SQL::Statement

    You can also look for information at:

    *   RT: CPAN's request tracker

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

    *   AnnoCPAN: Annotated CPAN documentation

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

    *   CPAN Ratings

        <http://cpanratings.perl.org/s/SQL-Statement>

    *   Search CPAN

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

  Where can I go for help?
    For questions about installation or usage, please ask on the dbi-users AT perl.org mailing list or
    post a question on PerlMonks (<http://www.perlmonks.org/>, where Jeff is known as jZed). Jens
    does not visit PerlMonks on a regular basis.

    If you have a bug report, a patch or a suggestion, please open a new report ticket at CPAN (but
    please check previous reports first in case your issue has already been addressed). You can mail
    any of the module maintainers, but you are more assured of an answer by posting to the dbi-users
    list or reporting the issue in RT.

    Report tickets should contain a detailed description of the bug or enhancement request and at
    least an easily verifiable way of reproducing the issue or fix. Patches are always welcome, too.

  Where can I go for help with a concrete version?
    Bugs and feature requests are accepted against the latest version only. To get patches for
    earlier versions, you need to get an agreement with a developer of your choice - who may or not
    report the the issue and a suggested fix upstream (depends on the license you have chosen).

  Business support and maintenance
    For business support you can contact Jens via his CPAN email address rehsackATcpan.org. Please
    keep in mind that business support is neither available for free nor are you eligible to receive
    any support based on the license distributed with this package.

AUTHOR & COPYRIGHT
     This module is

     copyright (c) 2001,2005 by Jeff Zucker and
     copyright (c) 2007-2020 by Jens Rehsack.

     All rights reserved.

    The module may be freely distributed under the same terms as Perl itself using either the "GPL
    License" or the "Artistic License" as specified in the Perl README file.

    Jeff can be reached at: jzuckerATcpan.org Jens can be reached at: rehsackATcpan.org or via
    dbi-devATperl.org