[Bast-commits] r5523 - DBIx-Class/0.08/branches/subquery/lib/DBIx/Class/Manual

[robkinyon at dev.catalyst.perl.org]

Author: robkinyon
Date: 2009-02-18 19:58:21 +0000 (Wed, 18 Feb 2009)
New Revision: 5523

Modified:
   DBIx-Class/0.08/branches/subquery/lib/DBIx/Class/Manual/Cookbook.pod
Log:
Added some more POD in the Cookbook for correlated subqueries

Modified: DBIx-Class/0.08/branches/subquery/lib/DBIx/Class/Manual/Cookbook.pod
===================================================================
--- DBIx-Class/0.08/branches/subquery/lib/DBIx/Class/Manual/Cookbook.pod	2009-02-18 19:54:31 UTC (rev 5522)
+++ DBIx-Class/0.08/branches/subquery/lib/DBIx/Class/Manual/Cookbook.pod	2009-02-18 19:58:21 UTC (rev 5523)
@@ -303,7 +303,7 @@
     name => [ 'Billy Joel', 'Brittany Spears' ],
   });
 
-  my $rs = $schema->resulset('CD')->search({
+  my $rs = $schema->resultset('CD')->search({
     artist_id => { 'IN' => $inside_rs->get_column('id')->as_query },
   });
 
@@ -312,10 +312,32 @@
 B<NOTE>: You have to explicitly use '=' when doing an equality comparison.
 The following will B<not> work:
 
-  my $rs = $schema->resulset('CD')->search({
+  my $rs = $schema->resultset('CD')->search({
     artist_id => $inside_rs->get_column('id')->as_query,
   });
 
+=head3 Correlated subqueries
+
+  my $cdrs = $schema->resultset('CD');
+  my $rs = $cdrs->search({
+    year => {
+      '=' => $cdrs->search(
+        { artistid => { '=' => \'me.artistid' } },
+        { alias => 'inner' }
+      )->get_column('year')->max_rs->as_query,
+    },
+  });
+
+That creates the following SQL:
+
+  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 artistid = me.artistid
+      )
+
 =head2 Predefined searches
 
 You can write your own L<DBIx::Class::ResultSet> class by inheriting from it