Data::Phrasebook::SQL(3) The SQL/DBI Phrasebook Model.

SYNOPSIS


use Data::Phrasebook;
use DBI;
my $dbh = DBI->connect(...);
my $book = Data::Phrasebook->new(
class => 'SQL',
dbh => $dbh,
file => 'queries.txt',
);
my $q = $book->query( 'find_author', {
author => "Lance Parkin"
});
while ( my $row = $q->fetchrow_hashref ) {
print "He wrote $row->{title}\n";
}
$q->finish;

queries.txt: 

    find_author=select title,author from books where author = :author

DESCRIPTION

In order to make use of features like placeholders in DBI in conjunction with phrasebooks, it's helpful to have a phrasebook be somewhat more aware of how DBI operates. Thus, you get "Data::Phrasebook::SQL".

"Data::Phrasebook::SQL" has knowledge of how DBI works and creates and executes your queries appropriately.

CONSTRUCTOR

new

Not to be accessed directly, but via the parent Data::Phrasebook, by specifying the class as SQL.

Additional arguments to those described in Data::Phrasebook::Generic are:

  • "dbh" - a DBI database handle.

METHODS

dbh

Set, or get, the current DBI handle.

query

Constructs a Data::Phrasebook::SQL::Query object from a template. Takes at least one argument, this being the identifier for the query. The identifier is used as a key into the phrasebook "file". A second argument can be provided, which is an optional hashref of key to value mappings.

If phrasebook has a YAML source looking much like the following: 

    ---
    find_author:
        sql: select class,title,author from books where author = :author

You could write: 

    my $q = $book->query( 'find_author' );
    OR
    my $q = $book->query( 'find_author', {
        author => 'Lance Parkin'
    } );
    OR
    my $author = 'Lance Parkin';
    my $q = $book->query( 'find_author', {
        author => \$author,
    } );
    # sql  = select class,title,author from books where author = ?
    # args = 'Lance Parkin'

In the above examples, the parameters are bound to the SQL using the bind parameters functionality. This is more efficient in most cases where the same SQL is reused with different values for fields.

However, not all SQL statements just need to bind parameters, some may require the ability to replace parameters, such as a field list. 

    ---
    find_author:
        sql: select :fields from books where author = :author
    my $q = $book->query( 'find_author',
        replace => { fields => 'class,title,author' },
        bind    => { author => 'Lance Parkin' }
        );
    # sql  = select class,title,author from books where author = ?
    # args = 'Lance Parkin'

In all instances, if the SQL template requested does not exist or has no definition, then an error will be thrown.

Consult Data::Phrasebook::SQL::Query for what you can then do with your returned object.

For reference: the bind hashref argument, if it is given, is given to the query object's "order_args" and then "args" methods.

SUPPORT

Please see the README file.

AUTHOR

  Original author: Iain Campbell Truskett (16.07.1979 - 29.12.2003)
  Maintainer: Barbie <[email protected]> since January 2004.
  for Miss Barbell Productions <http://www.missbarbell.co.uk>.

COPYRIGHT AND LICENSE

  Copyright (C) 2003 Iain Truskett.
  Copyright (C) 2004-2013 Barbie for Miss Barbell Productions.
  This distribution is free software; you can redistribute it and/or
  modify it under the Artistic License v2.

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