man DBIx::Class (3): Extensible and flexible object <-> relational mapper.

(3)

"DBIx-Class-Schema-Loader"
  package MyApp::Schema;
  use base qw/DBIx::Class::Schema/;
  __PACKAGE__->load_namespaces();
  1;

  package MyApp::Schema::Result::Artist;
  use base qw/DBIx::Class::Core/;
  __PACKAGE__->table('artist');
  __PACKAGE__->add_columns(qw/ artistid name /);
  __PACKAGE__->set_primary_key('artistid');
  __PACKAGE__->has_many(cds => 'MyApp::Schema::Result::CD', 'artistid');
  1;

  package MyApp::Schema::Result::CD;
  use base qw/DBIx::Class::Core/;
  __PACKAGE__->load_components(qw/InflateColumn::DateTime/);
  __PACKAGE__->table('cd');
  __PACKAGE__->add_columns(qw/ cdid artistid title year /);
  __PACKAGE__->set_primary_key('cdid');
  __PACKAGE__->belongs_to(artist => 'MyApp::Schema::Result::Artist', 'artistid');
  1;

  # Connect to your database.
  use MyApp::Schema;
  my $schema = MyApp::Schema->connect($dbi_dsn, $user, $pass, \%dbi_params);
  # Query for all artists and put them in an array,
  # or retrieve them as a result set object.
  # $schema->resultset returns a DBIx::Class::ResultSet
  my @all_artists = $schema->resultset('Artist')->all;
  my $all_artists_rs = $schema->resultset('Artist');
  # Output all artists names
  # $artist here is a DBIx::Class::Row, which has accessors
  # for all its columns. Rows are also subclasses of your Result class.
  foreach $artist (@all_artists) {
    print $artist->name, "\n";
  }
  # Create a result set to search for artists.
  # This does not query the DB.
  my $johns_rs = $schema->resultset('Artist')->search(
    # Build your WHERE using an SQL::Abstract structure:
    { name => { like => 'John%' } }
  );
  # Execute a joined query to get the cds.
  my @all_john_cds = $johns_rs->search_related('cds')->all;
  # Fetch the next available row.
  my $first_john = $johns_rs->next;
  # Specify ORDER BY on the query.
  my $first_john_cds_by_title_rs = $first_john->cds(
    undef,
    { order_by => 'title' }
  );
  # Create a result set that will fetch the artist data
  # at the same time as it fetches CDs, using only one query.
  my $millennium_cds_rs = $schema->resultset('CD')->search(
    { year => 2000 },
    { prefetch => 'artist' }
  );
  my $cd = $millennium_cds_rs->next; # SELECT ... FROM cds JOIN artists ...
  my $cd_artist_name = $cd->artist->name; # Already has the data so no 2nd query
  # new() makes a Result object but doesn't insert it into the DB.
  # create() is the same as new() then insert().
  my $new_cd = $schema->resultset('CD')->new({ title => 'Spoon' });
  $new_cd->artist($cd->artist);
  $new_cd->insert; # Auto-increment primary key filled in after INSERT
  $new_cd->title('Fork');
  $schema->txn_do(sub { $new_cd->update }); # Runs the update in a transaction
  # change the year of all the millennium CDs at once
  $millennium_cds_rs->update({ year => 2002 });

"JOIN"
"LEFT JOIN"
"COUNT"
"DISTINCT"
"GROUP BY"
"ORDER BY"
"HAVING"

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