__PACKAGE__->table_class('DBIx::Class::ResultSource::View');
- # ->table, ->add_columns, etc.
+ # For the time being this is necessary even for virtual views
+ __PACKAGE__->table($view_name);
+
+ #
+ # ->add_columns, etc.
+ #
# do not attempt to deploy() this view
__PACKAGE__->result_source_instance->is_virtual(1);
my $rs = $cdrs->search({
year => {
'=' => $cdrs->search(
- { artist_id => { '=' => { -ident => 'me.artist_id' } } },
- { alias => 'inner' }
+ { artist_id => { -ident => 'me.artist_id' } },
+ { alias => 'sub_query' }
)->get_column('year')->max_rs->as_query,
},
});
SELECT me.cdid, me.artist, me.title, me.year, me.genreid, me.single_track
FROM cd me
- WHERE year = (
- SELECT MAX(inner.year)
- FROM cd inner
- WHERE artist_id = me.artist_id
- )
+ WHERE year = (
+ SELECT MAX(sub_query.year)
+ FROM cd sub_query
+ WHERE artist_id = me.artist_id
+ )
=head2 Predefined searches
See also L<SQL::Abstract/Literal SQL with placeholders and bind values
(subqueries)>.
+=head2 Software Limits
+
+When your RDBMS does not have a working SQL limit mechanism (e.g. Sybase ASE)
+and L<GenericSubQ|SQL::Abstract::Limit/GenericSubQ> is either too slow or does
+not work at all, you can try the
+L<software_limit|DBIx::Class::ResultSet/software_limit>
+L<DBIx::Class::ResultSet> attribute, which skips over records to simulate limits
+in the Perl layer.
+
+For example:
+
+ my $paged_rs = $rs->search({}, {
+ rows => 25,
+ page => 3,
+ order_by => [ 'me.last_name' ],
+ software_limit => 1,
+ });
+
+You can set it as a default for your schema by placing the following in your
+C<Schema.pm>:
+
+ __PACKAGE__->default_resultset_attributes({ software_limit => 1 });
+
+B<WARNING:> If you are dealing with large resultsets and your L<DBI> or
+ODBC/ADO driver does not have proper cursor support (i.e. it loads the whole
+resultset into memory) then this feature will be extremely slow and use huge
+amounts of memory at best, and may cause your process to run out of memory and
+cause instability on your server at worst, beware!
+
=head1 JOINS AND PREFETCHING
=head2 Using joins and prefetch
__PACKAGE__->has_many('pages' => 'Page', 'book', { where => { scrap => 0 } } );
-=head2 Many-to-many relationships
+=head2 Many-to-many relationship bridges
This is straightforward using L<ManyToMany|DBIx::Class::Relationship/many_to_many>: