X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FManual%2FCookbook.pod;h=fae1e9461eb25e4dbcbfeb153762f770cc8f848f;hb=336256bc90f8b0493251c4fd7d88c3cdf02f636c;hp=70e645cac577fd4e8277dee95d55634fceba135a;hpb=e60dc79fcd4d6318e83584b826526e65048b86a9;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/Manual/Cookbook.pod b/lib/DBIx/Class/Manual/Cookbook.pod
index 70e645c..fae1e94 100644
--- a/lib/DBIx/Class/Manual/Cookbook.pod
+++ b/lib/DBIx/Class/Manual/Cookbook.pod
@@ -2,14 +2,12 @@
 
 DBIx::Class::Manual::Cookbook - Miscellaneous recipes
 
-=head1 RECIPES
+=head1 SEARCHING
 
-=head2 Searching
-
-=head3 Paged results
+=head2 Paged results
 
 When you expect a large number of results, you can ask L<DBIx::Class> for a
-paged resultset, which will fetch only a small number of records at a time:
+paged resultset, which will fetch only a defined number of records at a time:
 
   my $rs = $schema->resultset('Artist')->search(
     undef,
@@ -21,23 +19,12 @@ paged resultset, which will fetch only a small number of records at a time:
 
   return $rs->all(); # all records for page 1
 
-The C<page> attribute does not have to be specified in your search:
-
-  my $rs = $schema->resultset('Artist')->search(
-    undef,
-    {
-      rows => 10,
-    }
-  );
-
-  return $rs->page(1); # DBIx::Class::ResultSet containing first 10 records
-
-In either of the above cases, you can return a L<Data::Page> object for the
-resultset (suitable for use in e.g. a template) using the C<pager> method:
+You can get a L<Data::Page> object for the resultset (suitable for use
+in e.g. a template) using the C<pager> method:
 
   return $rs->pager();
 
-=head3 Complex WHERE clauses
+=head2 Complex WHERE clauses
 
 Sometimes you need to formulate a query using specific operators:
 
@@ -70,7 +57,42 @@ This results in the following C<WHERE> clause:
 For more information on generating complex queries, see
 L<SQL::Abstract/WHERE CLAUSES>.
 
-=head3 Arbitrary SQL through a custom ResultSource
+=head2 Retrieve one and only one row from a resultset
+
+Sometimes you need only the first "top" row of a resultset. While this can be
+easily done with L<< $rs->first|DBIx::Class::ResultSet/first >>, it is suboptimal,
+as a full blown cursor for the resultset will be created and then immediately
+destroyed after fetching the first row object. 
+L<< $rs->single|DBIx::Class::ResultSet/single >> is
+designed specifically for this case - it will grab the first returned result
+without even instantiating a cursor. 
+
+Before replacing all your calls to C<first()> with C<single()> please observe the 
+following CAVEATS:
+
+=over
+
+=item *
+While single() takes a search condition just like search() does, it does
+_not_ accept search attributes. However one can always chain a single() to
+a search():
+
+  my $top_cd = $cd_rs -> search({}, { order_by => 'rating' }) -> single;
+
+
+=item *
+Since single() is the engine behind find(), it is designed to fetch a
+single row per database query. Thus a warning will be issued when the
+underlying SELECT returns more than one row. Sometimes however this usage
+is valid: i.e. we have an arbitrary number of cd's but only one of them is
+at the top of the charts at any given time. If you know what you are doing,
+you can silence the warning by explicitly limiting the resultset size:
+
+  my $top_cd = $cd_rs -> search ({}, { order_by => 'rating', rows => 1 }) -> single;
+
+=back
+
+=head2 Arbitrary SQL through a custom ResultSource
 
 Sometimes you have to run arbitrary SQL because your query is too complex
 (e.g. it contains Unions, Sub-Selects, Stored Procedures, etc.) or has to
@@ -108,7 +130,7 @@ you have to add to your User class:
   SQL 
 
   # Finally, register your new ResultSource with your Schema
-  My::Schema->register_source( 'UserFriendsComplex' => $new_source );
+  My::Schema->register_extra_source( 'UserFriendsComplex' => $new_source );
 
 Next, you can execute your complex query using bind parameters like this:
 
@@ -118,9 +140,38 @@ Next, you can execute your complex query using bind parameters like this:
     }
   ) ];
   
-... and you'll get back a perfect L<DBIx::Class::ResultSet>.
+... and you'll get back a perfect L<DBIx::Class::ResultSet> (except, of course,
+that you cannot modify the rows it contains, ie. cannot call L</update>,
+L</delete>, ...  on it).
+
+If you prefer to have the definitions of these custom ResultSources in separate
+files (instead of stuffing all of them into the same resultset class), you can
+achieve the same with subclassing the resultset class and defining the
+ResultSource there:
+
+  package My::Schema::UserFriendsComplex;
+
+  use My::Schema::User;
+  use base qw/My::Schema::User/;
+
+  __PACKAGE__->table('dummy');  # currently must be called before anything else
 
-=head3 Using specific columns
+  # Hand in your query as a scalar reference
+  # It will be added as a sub-select after FROM,
+  # so pay attention to the surrounding brackets!
+  __PACKAGE__->name( \<<SQL );
+  ( SELECT u.* FROM user u
+  INNER JOIN user_friends f ON u.id = f.user_id
+  WHERE f.friend_user_id = ?
+  UNION
+  SELECT u.* FROM user u
+  INNER JOIN user_friends f ON u.id = f.friend_user_id
+  WHERE f.user_id = ? )
+  SQL
+
+TIMTOWDI.
+
+=head2 Using specific columns
 
 When you only want specific columns from a table, you can use
 C<columns> to specify which ones you need. This is useful to avoid
@@ -140,7 +191,7 @@ use anyway:
 This is a shortcut for C<select> and C<as>, see below. C<columns>
 cannot be used together with C<select> and C<as>.
 
-=head3 Using database functions or stored procedures
+=head2 Using database functions or stored procedures
 
 The combination of C<select> and C<as> can be used to return the result of a
 database function or stored procedure as a column value. You use C<select> to
@@ -184,7 +235,7 @@ any of your aliases using either of these:
   # Or use DBIx::Class::AccessorGroup:
   __PACKAGE__->mk_group_accessors('column' => 'name_length');
 
-=head3 SELECT DISTINCT with multiple columns
+=head2 SELECT DISTINCT with multiple columns
 
   my $rs = $schema->resultset('Foo')->search(
     {},
@@ -196,9 +247,7 @@ any of your aliases using either of these:
     }
   );
 
-  my $count = $rs->next->get_column('count');
-
-=head3 SELECT COUNT(DISTINCT colname)
+=head2 SELECT COUNT(DISTINCT colname)
 
   my $rs = $schema->resultset('Foo')->search(
     {},
@@ -210,7 +259,9 @@ any of your aliases using either of these:
     }
   );
 
-=head3 Grouping results
+  my $count = $rs->next->get_column('count');
+
+=head2 Grouping results
 
 L<DBIx::Class> supports C<GROUP BY> as follows:
 
@@ -218,22 +269,74 @@ L<DBIx::Class> supports C<GROUP BY> as follows:
     {},
     {
       join     => [qw/ cds /],
-      select   => [ 'name', { count => 'cds.cdid' } ],
+      select   => [ 'name', { count => 'cds.id' } ],
       as       => [qw/ name cd_count /],
       group_by => [qw/ name /]
     }
   );
 
   # Equivalent SQL:
-  # SELECT name, COUNT( cds.cdid ) FROM artist me
-  # LEFT JOIN cd cds ON ( cds.artist = me.artistid )
+  # SELECT name, COUNT( cd.id ) FROM artist
+  # LEFT JOIN cd ON artist.id = cd.artist
   # GROUP BY name
 
 Please see L<DBIx::Class::ResultSet/ATTRIBUTES> documentation if you
 are in any way unsure about the use of the attributes above (C< join
 >, C< select >, C< as > and C< group_by >).
 
-=head3 Predefined searches
+=head2 Subqueries (EXPERIMENTAL)
+
+You can write subqueries relatively easily in DBIC.
+
+  my $inside_rs = $schema->resultset('Artist')->search({
+    name => [ 'Billy Joel', 'Brittany Spears' ],
+  });
+
+  my $rs = $schema->resultset('CD')->search({
+    artist_id => { 'IN' => $inside_rs->get_column('id')->as_query },
+  });
+
+The usual operators ( =, !=, IN, NOT IN, etc) are supported.
+
+B<NOTE>: You have to explicitly use '=' when doing an equality comparison.
+The following will B<not> work:
+
+  my $rs = $schema->resultset('CD')->search({
+    artist_id => $inside_rs->get_column('id')->as_query,
+  });
+
+=head3 Support
+
+Subqueries are supported in the where clause (first hashref), and in the
+from, select, and +select attributes.
+
+=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
+      )
+
+=head3 EXPERIMENTAL
+
+Please note that subqueries are considered an experimental feature.
+
+=head2 Predefined searches
 
 You can write your own L<DBIx::Class::ResultSet> class by inheriting from it
 and define often used searches as methods:
@@ -257,12 +360,52 @@ and define often used searches as methods:
 To use your resultset, first tell DBIx::Class to create an instance of it
 for you, in your My::DBIC::Schema::CD class:
 
+  # class definition as normal
+  __PACKAGE__->load_components(qw/ Core /);
+  __PACKAGE__->table('cd');
+
+  # tell DBIC to use the custom ResultSet class
   __PACKAGE__->resultset_class('My::DBIC::ResultSet::CD');
 
+Note that C<resultset_class> must be called after C<load_components> and C<table>, or you will get errors about missing methods.
+
 Then call your new method in your code:
 
    my $ordered_cds = $schema->resultset('CD')->search_cds_ordered();
 
+=head2 Using SQL functions on the left hand side of a comparison
+
+Using SQL functions on the left hand side of a comparison is generally
+not a good idea since it requires a scan of the entire table.  However,
+it can be accomplished with C<DBIx::Class> when necessary.
+
+If you do not have quoting on, simply include the function in your search
+specification as you would any column:
+
+  $rs->search({ 'YEAR(date_of_birth)' => 1979 });
+
+With quoting on, or for a more portable solution, use the C<where>
+attribute:
+
+  $rs->search({}, { where => \'YEAR(date_of_birth) = 1979' });
+
+=begin hidden
+
+(When the bind args ordering bug is fixed, this technique will be better
+and can replace the one above.)
+
+With quoting on, or for a more portable solution, use the C<where> and
+C<bind> attributes:
+
+  $rs->search({}, {
+      where => \'YEAR(date_of_birth) = ?',
+      bind  => [ 1979 ]
+  });
+
+=end hidden
+
+=head1 JOINS AND PREFETCHING
+
 =head2 Using joins and prefetch
 
 You can use the C<join> attribute to allow searching on, or sorting your
@@ -274,7 +417,7 @@ a particular artist name:
       'artist.name' => 'Bob Marley'    
     },
     {
-      join => [qw/artist/], # join the artist table
+      join => 'artist', # join the artist table
     }
   );
 
@@ -291,10 +434,10 @@ it in your C<order_by> attribute:
       'artist.name' => 'Bob Marley'
     },
     {
-      join     => [qw/ artist /],
+      join     => 'artist',
       order_by => [qw/ artist.name /]
     }
-  };
+  );
 
   # Equivalent SQL:
   # SELECT cd.* FROM cd
@@ -332,9 +475,9 @@ This allows you to fetch results from related tables in advance:
       'artist.name' => 'Bob Marley'
     },
     {
-      join     => [qw/ artist /],
+      join     => 'artist',
       order_by => [qw/ artist.name /],
-      prefetch => [qw/ artist /] # return artist data too!
+      prefetch => 'artist' # return artist data too!
     }
   );
 
@@ -361,7 +504,35 @@ Also note that C<prefetch> should only be used when you know you will
 definitely use data from a related table. Pre-fetching related tables when you
 only need columns from the main table will make performance worse!
 
-=head3 Multi-step joins
+=head2 Multiple joins
+
+In the examples above, the C<join> attribute was a scalar.  If you
+pass an array reference instead, you can join to multiple tables.  In
+this example, we want to limit the search further, using
+C<LinerNotes>:
+
+  # Relationships defined elsewhere:
+  # CD->belongs_to('artist' => 'Artist');
+  # CD->has_one('liner_notes' => 'LinerNotes', 'cd');
+  my $rs = $schema->resultset('CD')->search(
+    {
+      'artist.name' => 'Bob Marley'
+      'liner_notes.notes' => { 'like', '%some text%' },
+    },
+    {
+      join     => [qw/ artist liner_notes /],
+      order_by => [qw/ artist.name /],
+    }
+  );
+
+  # Equivalent SQL:
+  # SELECT cd.*, artist.*, liner_notes.* FROM cd
+  # JOIN artist ON cd.artist = artist.id
+  # JOIN liner_notes ON cd.id = liner_notes.cd
+  # WHERE artist.name = 'Bob Marley'
+  # ORDER BY artist.name
+
+=head2 Multi-step joins
 
 Sometimes you want to join more than one relationship deep. In this example,
 we want to find all C<Artist> objects who have C<CD>s whose C<LinerNotes>
@@ -384,8 +555,8 @@ contain a specific string:
 
   # Equivalent SQL:
   # SELECT artist.* FROM artist
-  # JOIN ( cd ON artist.id = cd.artist )
-  # JOIN ( liner_notes ON cd.id = liner_notes.cd )
+  # LEFT JOIN cd ON artist.id = cd.artist
+  # LEFT JOIN liner_notes ON cd.id = liner_notes.cd
   # WHERE liner_notes.notes LIKE '%some text%'
 
 Joins can be nested to an arbitrary level. So if we decide later that we
@@ -411,12 +582,39 @@ notes:
 
   # Equivalent SQL:
   # SELECT artist.* FROM artist
-  # JOIN ( cd ON artist.id = cd.artist )
-  # JOIN ( liner_notes ON cd.id = liner_notes.cd )
-  # JOIN ( author ON author.id = liner_notes.author )
+  # LEFT JOIN cd ON artist.id = cd.artist
+  # LEFT JOIN liner_notes ON cd.id = liner_notes.cd
+  # LEFT JOIN author ON author.id = liner_notes.author
   # WHERE liner_notes.notes LIKE '%some text%'
   # AND author.name = 'A. Writer'
 
+=head2 Multi-step and multiple joins
+
+With various combinations of array and hash references, you can join
+tables in any combination you desire.  For example, to join Artist to
+CD and Concert, and join CD to LinerNotes:
+
+  # Relationships defined elsewhere:
+  # Artist->has_many('concerts' => 'Concert', 'artist');
+
+  my $rs = $schema->resultset('Artist')->search(
+    { },
+    {
+      join => [
+        {
+          cds => 'liner_notes'
+        },
+        'concerts'
+      ],
+    }
+  );
+
+  # Equivalent SQL:
+  # SELECT artist.* FROM artist
+  # LEFT JOIN cd ON artist.id = cd.artist
+  # LEFT JOIN liner_notes ON cd.id = liner_notes.cd
+  # LEFT JOIN concert ON artist.id = concert.artist
+
 =head2 Multi-step prefetch
 
 From 0.04999_05 onwards, C<prefetch> can be nested more than one relationship
@@ -433,8 +631,8 @@ deep using the same syntax as a multi-step join:
 
   # Equivalent SQL:
   # SELECT tag.*, cd.*, artist.* FROM tag
-  # JOIN cd ON tag.cd = cd.cdid
-  # JOIN artist ON cd.artist = artist.artistid
+  # JOIN cd ON tag.cd = cd.id
+  # JOIN artist ON cd.artist = artist.id
 
 Now accessing our C<cd> and C<artist> relationships does not need additional
 SQL statements:
@@ -442,289 +640,627 @@ SQL statements:
   my $tag = $rs->first;
   print $tag->cd->artist->name;
 
-=head2 Columns of data
-
-If you want to find the sum of a particular column there are several
-ways, the obvious one is to use search:
-
-  my $rs = $schema->resultset('Items')->search(
-    {},
-    { 
-       select => [ { sum => 'Cost' } ],
-       as     => [ 'total_cost' ], # remember this 'as' is for DBIx::Class::ResultSet not SQL
-    }
-  );
-  my $tc = $rs->first->get_column('total_cost');
-
-Or, you can use the L<DBIx::Class::ResultSetColumn>, which gets
-returned when you ask the C<ResultSet> for a column using
-C<get_column>:
-
-  my $cost = $schema->resultset('Items')->get_column('Cost');
-  my $tc = $cost->sum;
-
-With this you can also do:
-
-  my $minvalue = $cost->min;
-  my $maxvalue = $cost->max;
-
-Or just iterate through the values of this column only:
-
-  while ( my $c = $cost->next ) {
-    print $c;
-  }
-
-  foreach my $c ($cost->all) {
-    print $c;
-  }
+=head1 ROW-LEVEL OPERATIONS
 
-C<ResultSetColumn> only has a limited number of built-in functions, if
-you need one that it doesn't have, then you can use the C<func> method
-instead:
+=head2 Retrieving a row object's Schema
 
-  my $avg = $cost->func('AVERAGE');
+It is possible to get a Schema object from a row object like so:
 
-This will cause the following SQL statement to be run:
+  my $schema = $cd->result_source->schema;
+  # use the schema as normal:
+  my $artist_rs = $schema->resultset('Artist'); 
 
-  SELECT AVERAGE(Cost) FROM Items me
+This can be useful when you don't want to pass around a Schema object to every
+method.
 
-Which will of course only work if your database supports this function.
-See L<DBIx::Class::ResultSetColumn> for more documentation.
+=head2 Getting the value of the primary key for the last database insert
 
-=head2 Using relationships
+AKA getting last_insert_id
 
-=head3 Create a new row in a related table
+If you are using PK::Auto (which is a core component as of 0.07), this is 
+straightforward:
 
-  my $book->create_related('author', { name => 'Fred'});
+  my $foo = $rs->create(\%blah);
+  # do more stuff
+  my $id = $foo->id; # foo->my_primary_key_field will also work.
 
-=head3 Search in a related table
+If you are not using autoincrementing primary keys, this will probably
+not work, but then you already know the value of the last primary key anyway.
 
-Only searches for books named 'Titanic' by the author in $author.
+=head2 Stringification
 
-  my $author->search_related('books', { name => 'Titanic' });
+Employ the standard stringification technique by using the C<overload>
+module.
 
-=head3 Delete data in a related table
+To make an object stringify itself as a single column, use something
+like this (replace C<foo> with the column/method of your choice):
 
-Deletes only the book named Titanic by the author in $author.
+  use overload '""' => sub { shift->name}, fallback => 1;
 
-  my $author->delete_related('books', { name => 'Titanic' });
+For more complex stringification, you can use an anonymous subroutine:
 
-=head3 Ordering a relationship result set
+  use overload '""' => sub { $_[0]->name . ", " .
+                             $_[0]->address }, fallback => 1;
 
-If you always want a relation to be ordered, you can specify this when you 
-create the relationship.
+=head3 Stringification Example
 
-To order C<< $book->pages >> by descending page_number.
+Suppose we have two tables: C<Product> and C<Category>. The table
+specifications are:
 
-  Book->has_many('pages' => 'Page', 'book', { order_by => \'page_number DESC'} );
+  Product(id, Description, category)
+  Category(id, Description)
 
+C<category> is a foreign key into the Category table.
 
+If you have a Product object C<$obj> and write something like
 
-=head2 Transactions
+  print $obj->category
 
-As of version 0.04001, there is improved transaction support in
-L<DBIx::Class::Storage> and L<DBIx::Class::Schema>.  Here is an
-example of the recommended way to use it:
+things will not work as expected.
 
-  my $genus = $schema->resultset('Genus')->find(12);
+To obtain, for example, the category description, you should add this
+method to the class defining the Category table:
 
-  my $coderef2 = sub {
-    $genus->extinct(1);
-    $genus->update;
-  };
+  use overload "" => sub {
+      my $self = shift;
 
-  my $coderef1 = sub {
-    $genus->add_to_species({ name => 'troglodyte' });
-    $genus->wings(2);
-    $genus->update;
-    $schema->txn_do($coderef2); # Can have a nested transaction
-    return $genus->species;
-  };
+      return $self->Description;
+  }, fallback => 1;
 
-  my $rs;
-  eval {
-    $rs = $schema->txn_do($coderef1);
-  };
+=head2 Want to know if find_or_create found or created a row?
 
-  if ($@) {                             # Transaction failed
-    die "the sky is falling!"           #
-      if ($@ =~ /Rollback failed/);     # Rollback failed
+Just use C<find_or_new> instead, then check C<in_storage>:
 
-    deal_with_failed_transaction();
+  my $obj = $rs->find_or_new({ blah => 'blarg' });
+  unless ($obj->in_storage) {
+    $obj->insert;
+    # do whatever else you wanted if it was a new row
   }
 
-Nested transactions will work as expected. That is, only the outermost
-transaction will actually issue a commit to the $dbh, and a rollback
-at any level of any transaction will cause the entire nested
-transaction to fail. Support for savepoints and for true nested
-transactions (for databases that support them) will hopefully be added
-in the future.
-
-=head2 Many-to-many relationships
-
-This is straightforward using L<ManyToMany|DBIx::Class::Relationship/many_to_many>:
-
-  package My::DB;
-  # ... set up connection ...
-
-  package My::User;
-  use base 'My::DB';
-  __PACKAGE__->table('user');
-  __PACKAGE__->add_columns(qw/id name/);
-  __PACKAGE__->set_primary_key('id');
-  __PACKAGE__->has_many('user_address' => 'My::UserAddress', 'user');
-  __PACKAGE__->many_to_many('addresses' => 'user_address', 'address');
+=head2 Dynamic Sub-classing DBIx::Class proxy classes 
 
-  package My::UserAddress;
-  use base 'My::DB';
-  __PACKAGE__->table('user_address');
-  __PACKAGE__->add_columns(qw/user address/);
-  __PACKAGE__->set_primary_key(qw/user address/);
-  __PACKAGE__->belongs_to('user' => 'My::User');
-  __PACKAGE__->belongs_to('address' => 'My::Address');
+AKA multi-class object inflation from one table
+ 
+L<DBIx::Class> classes are proxy classes, therefore some different
+techniques need to be employed for more than basic subclassing.  In
+this example we have a single user table that carries a boolean bit
+for admin.  We would like like to give the admin users
+objects(L<DBIx::Class::Row>) the same methods as a regular user but
+also special admin only methods.  It doesn't make sense to create two
+seperate proxy-class files for this.  We would be copying all the user
+methods into the Admin class.  There is a cleaner way to accomplish
+this.
 
-  package My::Address;
-  use base 'My::DB';
-  __PACKAGE__->table('address');
-  __PACKAGE__->add_columns(qw/id street town area_code country/);
-  __PACKAGE__->set_primary_key('id');
+Overriding the C<inflate_result> method within the User proxy-class
+gives us the effect we want.  This method is called by
+L<DBIx::Class::ResultSet> when inflating a result from storage.  So we
+grab the object being returned, inspect the values we are looking for,
+bless it if it's an admin object, and then return it.  See the example
+below:
+ 
+B<Schema Definition> 
+ 
+    package DB::Schema; 
+     
+    use base qw/DBIx::Class::Schema/; 
+ 
+    __PACKAGE__->load_classes(qw/User/); 
+ 
+ 
+B<Proxy-Class definitions> 
+ 
+    package DB::Schema::User; 
+     
+    use strict; 
+    use warnings; 
+    use base qw/DBIx::Class/; 
+     
+    ### Defined what our admin class is for ensure_class_loaded 
+    my $admin_class = __PACKAGE__ . '::Admin'; 
+     
+    __PACKAGE__->load_components(qw/Core/); 
+     
+    __PACKAGE__->table('users'); 
+     
+    __PACKAGE__->add_columns(qw/user_id   email    password  
+                                firstname lastname active 
+                                admin/); 
+     
+    __PACKAGE__->set_primary_key('user_id'); 
+     
+    sub inflate_result { 
+        my $self = shift;  
+        my $ret = $self->next::method(@_); 
+        if( $ret->admin ) {### If this is an admin rebless for extra functions  
+            $self->ensure_class_loaded( $admin_class ); 
+            bless $ret, $admin_class; 
+        } 
+        return $ret; 
+    } 
+     
+    sub hello { 
+        print "I am a regular user.\n"; 
+        return ; 
+    } 
+     
+     
+    package DB::Schema::User::Admin; 
+     
+    use strict; 
+    use warnings; 
+    use base qw/DB::Schema::User/; 
+     
+    sub hello 
+    { 
+        print "I am an admin.\n"; 
+        return; 
+    } 
+     
+    sub do_admin_stuff 
+    { 
+        print "I am doing admin stuff\n"; 
+        return ; 
+    } 
+ 
+B<Test File> test.pl 
+ 
+    use warnings; 
+    use strict; 
+    use DB::Schema; 
+     
+    my $user_data = { email    => 'someguy@place.com',  
+                      password => 'pass1',  
+                      admin    => 0 }; 
+                           
+    my $admin_data = { email    => 'someadmin@adminplace.com',  
+                       password => 'pass2',  
+                       admin    => 1 }; 
+                           
+    my $schema = DB::Schema->connection('dbi:Pg:dbname=test'); 
+     
+    $schema->resultset('User')->create( $user_data ); 
+    $schema->resultset('User')->create( $admin_data ); 
+     
+    ### Now we search for them 
+    my $user = $schema->resultset('User')->single( $user_data ); 
+    my $admin = $schema->resultset('User')->single( $admin_data ); 
+     
+    print ref $user, "\n"; 
+    print ref $admin, "\n"; 
+     
+    print $user->password , "\n"; # pass1 
+    print $admin->password , "\n";# pass2; inherited from User 
+    print $user->hello , "\n";# I am a regular user. 
+    print $admin->hello, "\n";# I am an admin. 
+ 
+    ### The statement below will NOT print 
+    print "I can do admin stuff\n" if $user->can('do_admin_stuff'); 
+    ### The statement below will print 
+    print "I can do admin stuff\n" if $admin->can('do_admin_stuff'); 
+
+=head2 Skip row object creation for faster results
+
+DBIx::Class is not built for speed, it's built for convenience and
+ease of use, but sometimes you just need to get the data, and skip the
+fancy objects.
+  
+To do this simply use L<DBIx::Class::ResultClass::HashRefInflator>.
+  
+ my $rs = $schema->resultset('CD');
+ 
+ $rs->result_class('DBIx::Class::ResultClass::HashRefInflator');
+ 
+ my $hash_ref = $rs->find(1);
+
+Wasn't that easy?
+
+=head2 Get raw data for blindingly fast results
+
+If the L<HashRefInflator|DBIx::Class::ResultClass::HashRefInflator> solution
+above is not fast enough for you, you can use a DBIx::Class to return values
+exactly as they come out of the data base with none of the convenience methods
+wrapped round them.
+
+This is used like so:
+
+  my $cursor = $rs->cursor
+  while (my @vals = $cursor->next) {
+      # use $val[0..n] here
+  }
+
+You will need to map the array offsets to particular columns (you can
+use the I<select> attribute of C<search()> to force ordering).
+
+=head1 RESULTSET OPERATIONS
+
+=head2 Getting Schema from a ResultSet
+
+To get the schema object from a result set, do the following:
+
+ $rs->result_source->schema
+
+=head2 Getting Columns Of Data
+
+AKA Aggregating Data
+
+If you want to find the sum of a particular column there are several
+ways, the obvious one is to use search:
+
+  my $rs = $schema->resultset('Items')->search(
+    {},
+    { 
+       select => [ { sum => 'Cost' } ],
+       as     => [ 'total_cost' ], # remember this 'as' is for DBIx::Class::ResultSet not SQL
+    }
+  );
+  my $tc = $rs->first->get_column('total_cost');
+
+Or, you can use the L<DBIx::Class::ResultSetColumn>, which gets
+returned when you ask the C<ResultSet> for a column using
+C<get_column>:
+
+  my $cost = $schema->resultset('Items')->get_column('Cost');
+  my $tc = $cost->sum;
+
+With this you can also do:
+
+  my $minvalue = $cost->min;
+  my $maxvalue = $cost->max;
+
+Or just iterate through the values of this column only:
+
+  while ( my $c = $cost->next ) {
+    print $c;
+  }
+
+  foreach my $c ($cost->all) {
+    print $c;
+  }
+
+C<ResultSetColumn> only has a limited number of built-in functions, if
+you need one that it doesn't have, then you can use the C<func> method
+instead:
+
+  my $avg = $cost->func('AVERAGE');
+
+This will cause the following SQL statement to be run:
+
+  SELECT AVERAGE(Cost) FROM Items me
+
+Which will of course only work if your database supports this function.
+See L<DBIx::Class::ResultSetColumn> for more documentation.
+
+=head2 Creating a result set from a set of rows
+
+Sometimes you have a (set of) row objects that you want to put into a 
+resultset without the need to hit the DB again. You can do that by using the
+L<set_cache|DBIx::Class::Resultset/set_cache> method:
+
+ my @uploadable_groups;
+ while (my $group = $groups->next) {
+   if ($group->can_upload($self)) {
+     push @uploadable_groups, $group;
+   }
+ }
+ my $new_rs = $self->result_source->resultset;
+ $new_rs->set_cache(\@uploadable_groups);
+ return $new_rs;
+
+
+=head1 USING RELATIONSHIPS
+
+=head2 Create a new row in a related table
+
+  my $author = $book->create_related('author', { name => 'Fred'});
+
+=head2 Search in a related table
+
+Only searches for books named 'Titanic' by the author in $author.
+
+  my $books_rs = $author->search_related('books', { name => 'Titanic' });
+
+=head2 Delete data in a related table
+
+Deletes only the book named Titanic by the author in $author.
+
+  $author->delete_related('books', { name => 'Titanic' });
+
+=head2 Ordering a relationship result set
+
+If you always want a relation to be ordered, you can specify this when you 
+create the relationship.
+
+To order C<< $book->pages >> by descending page_number, create the relation
+as follows:
+
+  __PACKAGE__->has_many('pages' => 'Page', 'book', { order_by => \'page_number DESC'} );
+
+=head2 Filtering a relationship result set
+
+If you want to get a filtered result set, you can just add add to $attr as follows:
+
+ __PACKAGE__->has_many('pages' => 'Page', 'book', { where => { scrap => 0 } } );
+
+=head2 Many-to-many relationships
+
+This is straightforward using L<ManyToMany|DBIx::Class::Relationship/many_to_many>:
+
+  package My::User;
+  use base 'DBIx::Class';
+  __PACKAGE__->load_components('Core');
+  __PACKAGE__->table('user');
+  __PACKAGE__->add_columns(qw/id name/);
+  __PACKAGE__->set_primary_key('id');
+  __PACKAGE__->has_many('user_address' => 'My::UserAddress', 'user');
+  __PACKAGE__->many_to_many('addresses' => 'user_address', 'address');
+
+  package My::UserAddress;
+  use base 'DBIx::Class';
+  __PACKAGE__->load_components('Core');
+  __PACKAGE__->table('user_address');
+  __PACKAGE__->add_columns(qw/user address/);
+  __PACKAGE__->set_primary_key(qw/user address/);
+  __PACKAGE__->belongs_to('user' => 'My::User');
+  __PACKAGE__->belongs_to('address' => 'My::Address');
+
+  package My::Address;
+  use base 'DBIx::Class';
+  __PACKAGE__->load_components('Core');
+  __PACKAGE__->table('address');
+  __PACKAGE__->add_columns(qw/id street town area_code country/);
+  __PACKAGE__->set_primary_key('id');
   __PACKAGE__->has_many('user_address' => 'My::UserAddress', 'address');
   __PACKAGE__->many_to_many('users' => 'user_address', 'user');
 
   $rs = $user->addresses(); # get all addresses for a user
   $rs = $address->users(); # get all users for an address
 
-=head2 Setting default values for a row
+=head1 TRANSACTIONS
 
-It's as simple as overriding the C<new> method.  Note the use of
-C<next::method>.
+As of version 0.04001, there is improved transaction support in
+L<DBIx::Class::Storage> and L<DBIx::Class::Schema>.  Here is an
+example of the recommended way to use it:
 
-  sub new {
-    my ( $self, $attrs ) = @_;
+  my $genus = $schema->resultset('Genus')->find(12);
 
-    $attrs->{foo} = 'bar' unless defined $attrs->{foo};
+  my $coderef2 = sub {
+    $genus->extinct(1);
+    $genus->update;
+  };
 
-    my $new = $class->next::method($attrs);
+  my $coderef1 = sub {
+    $genus->add_to_species({ name => 'troglodyte' });
+    $genus->wings(2);
+    $genus->update;
+    $schema->txn_do($coderef2); # Can have a nested transaction. Only the outer will actualy commit
+    return $genus->species;
+  };
 
-    return $new;
+  my $rs;
+  eval {
+    $rs = $schema->txn_do($coderef1);
+  };
+
+  if ($@) {                             # Transaction failed
+    die "the sky is falling!"           #
+      if ($@ =~ /Rollback failed/);     # Rollback failed
+
+    deal_with_failed_transaction();
   }
 
-For more information about C<next::method>, look in the L<Class::C3> 
-documentation. See also L<DBIx::Class::Manual::Component> for more
-ways to write your own base classes to do this.
+Nested transactions will work as expected. That is, only the outermost
+transaction will actually issue a commit to the $dbh, and a rollback
+at any level of any transaction will cause the entire nested
+transaction to fail. Support for savepoints and for true nested
+transactions (for databases that support them) will hopefully be added
+in the future.
 
-People looking for ways to do "triggers" with DBIx::Class are probably
-just looking for this. 
+=head1 SQL 
 
-=head2 Stringification
+=head2 Creating Schemas From An Existing Database
 
-Employ the standard stringification technique by using the C<overload>
-module.
+L<DBIx::Class::Schema::Loader> will connect to a database and create a 
+L<DBIx::Class::Schema> and associated sources by examining the database.
 
-To make an object stringify itself as a single column, use something
-like this (replace C<foo> with the column/method of your choice):
+The recommend way of achieving this is to use the 
+L<make_schema_at|DBIx::Class::Schema::Loader/make_schema_at> method:
 
-  use overload '""' => sub { shift->name}, fallback => 1;
+  perl -MDBIx::Class::Schema::Loader=make_schema_at,dump_to_dir:./lib \
+    -e 'make_schema_at("My::Schema", { debug => 1 }, [ "dbi:Pg:dbname=foo","postgres" ])'
 
-For more complex stringification, you can use an anonymous subroutine:
+This will create a tree of files rooted at C<./lib/My/Schema/> containing
+source definitions for all the tables found in the C<foo> database.
 
-  use overload '""' => sub { $_[0]->name . ", " .
-                             $_[0]->address }, fallback => 1;
+=head2 Creating DDL SQL
 
-=head3 Stringification Example
+The following functionality requires you to have L<SQL::Translator>
+(also known as "SQL Fairy") installed.
 
-Suppose we have two tables: C<Product> and C<Category>. The table
-specifications are:
+To create a set of database-specific .sql files for the above schema:
 
-  Product(id, Description, category)
-  Category(id, Description)
+ my $schema = My::Schema->connect($dsn);
+ $schema->create_ddl_dir(['MySQL', 'SQLite', 'PostgreSQL'],
+                        '0.1',
+                        './dbscriptdir/'
+                        );
 
-C<category> is a foreign key into the Category table.
+By default this will create schema files in the current directory, for
+MySQL, SQLite and PostgreSQL, using the $VERSION from your Schema.pm.
 
-If you have a Product object C<$obj> and write something like
+To create a new database using the schema:
 
-  print $obj->category
+ my $schema = My::Schema->connect($dsn);
+ $schema->deploy({ add_drop_tables => 1});
 
-things will not work as expected.
+To import created .sql files using the mysql client:
 
-To obtain, for example, the category description, you should add this
-method to the class defining the Category table:
+  mysql -h "host" -D "database" -u "user" -p < My_Schema_1.0_MySQL.sql
 
-  use overload "" => sub {
-      my $self = shift;
+To create C<ALTER TABLE> conversion scripts to update a database to a
+newer version of your schema at a later point, first set a new
+C<$VERSION> in your Schema file, then:
 
-      return $self->Description;
-  }, fallback => 1;
+ my $schema = My::Schema->connect($dsn);
+ $schema->create_ddl_dir(['MySQL', 'SQLite', 'PostgreSQL'],
+                         '0.2',
+                         '/dbscriptdir/',
+                         '0.1'
+                         );
 
-=head2 Disconnecting cleanly
+This will produce new database-specific .sql files for the new version
+of the schema, plus scripts to convert from version 0.1 to 0.2. This
+requires that the files for 0.1 as created above are available in the
+given directory to diff against.
 
-If you find yourself quitting an app with Control-C a lot during
-development, you might like to put the following signal handler in
-your main database class to make sure it disconnects cleanly:
+=head2 Select from dual
 
-  $SIG{INT} = sub {
-    __PACKAGE__->storage->disconnect;
-  };
+Dummy tables are needed by some databases to allow calling functions
+or expressions that aren't based on table content, for examples of how
+this applies to various database types, see:
+L<http://troels.arvin.dk/db/rdbms/#other-dummy_table>.
 
-=head2 Schema import/export
+Note: If you're using Oracles dual table don't B<ever> do anything
+other than a select, if you CRUD on your dual table you *will* break
+your database.
 
-This functionality requires you to have L<SQL::Translator> (also known as
-"SQL Fairy") installed.
+Make a table class as you would for any other table
+                                                                               
+  package MyAppDB::Dual;
+  use strict;
+  use warnings;
+  use base 'DBIx::Class';
+  __PACKAGE__->load_components("Core");
+  __PACKAGE__->table("Dual");
+  __PACKAGE__->add_columns(
+    "dummy",
+    { data_type => "VARCHAR2", is_nullable => 0, size => 1 },
+  );
+ 
+Once you've loaded your table class select from it using C<select>
+and C<as> instead of C<columns>
+ 
+  my $rs = $schema->resultset('Dual')->search(undef,
+    { select => [ 'sydate' ],
+      as     => [ 'now' ]
+    },
+  );
+ 
+All you have to do now is be careful how you access your resultset, the below
+will not work because there is no column called 'now' in the Dual table class
+ 
+  while (my $dual = $rs->next) {
+    print $dual->now."\n";
+  }
+  # Can't locate object method "now" via package "MyAppDB::Dual" at headshot.pl line 23.
+ 
+You could of course use 'dummy' in C<as> instead of 'now', or C<add_columns> to
+your Dual class for whatever you wanted to select from dual, but that's just
+silly, instead use C<get_column>
+ 
+  while (my $dual = $rs->next) {
+    print $dual->get_column('now')."\n";
+  }
+ 
+Or use C<cursor>
+ 
+  my $cursor = $rs->cursor;
+  while (my @vals = $cursor->next) {
+    print $vals[0]."\n";
+  }
 
-To create a DBIx::Class schema from an existing database:
+In case you're going to use this "trick" together with L<DBIx::Class::Schema/deploy> or
+L<DBIx::Class::Schema/create_ddl_dir> a table called "dual" will be created in your
+current schema. This would overlap "sys.dual" and you could not fetch "sysdate" or
+"sequence.nextval" anymore from dual. To avoid this problem, just tell
+L<SQL::Translator> to not create table dual:
+
+    my $sqlt_args = {
+        add_drop_table => 1,
+        parser_args    => { sources => [ grep $_ ne 'Dual', schema->sources ] },
+    };
+    $schema->create_ddl_dir( [qw/Oracle/], undef, './sql', undef, $sqlt_args );
+ 
+Or use L<DBIx::Class::ResultClass::HashRefInflator>
+ 
+  $rs->result_class('DBIx::Class::ResultClass::HashRefInflator');
+  while ( my $dual = $rs->next ) {
+    print $dual->{now}."\n";
+  }
+ 
+Here are some example C<select> conditions to illustrate the different syntax
+you could use for doing stuff like 
+C<oracles.heavily(nested(functions_can('take', 'lots'), OF), 'args')>
+ 
+  # get a sequence value
+  select => [ 'A_SEQ.nextval' ],
+ 
+  # get create table sql
+  select => [ { 'dbms_metadata.get_ddl' => [ "'TABLE'", "'ARTIST'" ]} ],
+ 
+  # get a random num between 0 and 100
+  select => [ { "trunc" => [ { "dbms_random.value" => [0,100] } ]} ],
+ 
+  # what year is it?
+  select => [ { 'extract' => [ \'year from sysdate' ] } ],
+ 
+  # do some math
+  select => [ {'round' => [{'cos' => [ \'180 * 3.14159265359/180' ]}]}],
+ 
+  # which day of the week were you born on?
+  select => [{'to_char' => [{'to_date' => [ "'25-DEC-1980'", "'dd-mon-yyyy'" ]}, "'day'"]}],
+ 
+  # select 16 rows from dual
+  select   => [ "'hello'" ],
+  as       => [ 'world' ],
+  group_by => [ 'cube( 1, 2, 3, 4 )' ],
+ 
+ 
 
- sqlt --from DBI
-      --to DBIx::Class::File
-      --prefix "MySchema" > MySchema.pm
+=head2 Adding Indexes And Functions To Your SQL
 
-To create a MySQL database from an existing L<DBIx::Class> schema, convert the
-schema to MySQL's dialect of SQL:
+Often you will want indexes on columns on your table to speed up searching. To
+do this, create a method called C<sqlt_deploy_hook> in the relevant source 
+class (refer to the advanced 
+L<callback system|DBIx::Class::ResultSource/sqlt_deploy_callback> if you wish
+to share a hook between multiple sources):
 
-  sqlt --from SQL::Translator::Parser::DBIx::Class 
-       --to MySQL 
-       --DBIx::Class "MySchema.pm" > Schema1.sql
-  
-And import using the mysql client:
+ package My::Schema::Artist;
 
-  mysql -h "host" -D "database" -u "user" -p < Schema1.sql
+ __PACKAGE__->table('artist');
+ __PACKAGE__->add_columns(id => { ... }, name => { ... })
 
-=head2 Easy migration from class-based to schema-based setup
+ sub sqlt_deploy_hook {
+   my ($self, $sqlt_table) = @_;
 
-You want to start using the schema-based approach to L<DBIx::Class>
-(see L<SchemaIntro.pod>), but have an established class-based setup with lots
-of existing classes that you don't want to move by hand. Try this nifty script
-instead:
+   $sqlt_table->add_index(name => 'idx_name', fields => ['name']);
+ }
 
-  use MyDB;
-  use SQL::Translator;
-  
-  my $schema = MyDB->schema_instance;
-  
-  my $translator           =  SQL::Translator->new( 
-      debug                => $debug          ||  0,
-      trace                => $trace          ||  0,
-      no_comments          => $no_comments    ||  0,
-      show_warnings        => $show_warnings  ||  0,
-      add_drop_table       => $add_drop_table ||  0,
-      validate             => $validate       ||  0,
-      parser_args          => {
-         'DBIx::Schema'    => $schema,
-                              },
-      producer_args   => {
-          'prefix'         => 'My::Schema',
-                         },
-  );
-  
-  $translator->parser('SQL::Translator::Parser::DBIx::Class');
-  $translator->producer('SQL::Translator::Producer::DBIx::Class::File');
-  
-  my $output = $translator->translate(@args) or die
-          "Error: " . $translator->error;
-  
-  print $output;
+ 1;
+
+Sometimes you might want to change the index depending on the type of the 
+database for which SQL is being generated:
+
+  my ($db_type = $sqlt_table->schema->translator->producer_type)
+    =~ s/^SQL::Translator::Producer:://;
+
+You can also add hooks to the schema level to stop certain tables being 
+created:
+
+ package My::Schema;
+
+ ...
+
+ sub sqlt_deploy_hook {
+   my ($self, $sqlt_schema) = @_;
+
+   $sqlt_schema->drop_table('table_name');
+ }
+
+You could also add views, procedures or triggers to the output using
+L<SQL::Translator::Schema/add_view>,
+L<SQL::Translator::Schema/add_procedure> or
+L<SQL::Translator::Schema/add_trigger>.
 
-You could use L<Module::Find> to search for all subclasses in the MyDB::*
-namespace, which is currently left as an exercise for the reader.
 
 =head2 Schema versioning
 
@@ -755,28 +1291,16 @@ Deploy update to customers
 
 =back
 
-=head3 Create a DBIx::Class schema
+B<Create a DBIx::Class schema>
 
 This can either be done manually, or generated from an existing database as
-described under C<Schema import/export>.
+described under L</Creating Schemas From An Existing Database>
 
-=head3 Save the schema
+B<Save the schema>
 
-Use C<sqlt> to transform your schema into an SQL script suitable for your
-customer's database. E.g. for MySQL:
+Call L<DBIx::Class::Schema/create_ddl_dir> as above under L</Creating DDL SQL>.
 
-  sqlt --from SQL::Translator::Parser::DBIx::Class
-       --to MySQL
-       --DBIx::Class "MySchema.pm" > Schema1.mysql.sql
-
-If you need to target databases from multiple vendors, just generate an SQL
-script suitable for each. To support PostgreSQL too:
-
-  sqlt --from SQL::Translator::DBIx::Class
-       --to PostgreSQL
-       --DBIx::Class "MySchema.pm" > Schema1.pgsql.sql
-
-=head3 Deploy to customers
+B<Deploy to customers>
 
 There are several ways you could deploy your schema. These are probably
 beyond the scope of this recipe, but might include:
@@ -794,24 +1318,53 @@ all part of your install.
 
 =back
 
-=head3 Modify the schema to change functionality
+B<Modify the schema to change functionality>
+
+As your application evolves, it may be necessary to modify your schema
+to change functionality. Once the changes are made to your schema in
+DBIx::Class, export the modified schema and the conversion scripts as
+in L</Creating DDL SQL>.
 
-As your application evolves, it may be necessary to modify your schema to
-change functionality. Once the changes are made to your schema in DBIx::Class,
-export the modified schema as before, taking care not to overwrite the original:
+B<Deploy update to customers>
 
-  sqlt --from SQL::Translator::DBIx::Class
-       --to MySQL
-       --DBIx::Class "Anything.pm" > Schema2.mysql.sql
+Add the L<DBIx::Class::Schema::Versioned> schema component to your
+Schema class. This will add a new table to your database called
+C<dbix_class_schema_vesion> which will keep track of which version is installed
+and warn if the user trys to run a newer schema version than the
+database thinks it has.
+
+Alternatively, you can send the conversion sql scripts to your
+customers as above.
+
+=head2 Setting quoting for the generated SQL. 
 
-Next, use sqlt-diff to create an SQL script that will update the customer's
-database schema:
+If the database contains column names with spaces and/or reserved words, they
+need to be quoted in the SQL queries. This is done using:
+
+ __PACKAGE__->storage->sql_maker->quote_char([ qw/[ ]/] );
+ __PACKAGE__->storage->sql_maker->name_sep('.');
+
+The first sets the quote characters. Either a pair of matching
+brackets, or a C<"> or C<'>:
+  
+ __PACKAGE__->storage->sql_maker->quote_char('"');
 
-  sqlt-diff --to MySQL Schema1=MySQL Schema2=MySQL > SchemaUpdate.mysql.sql
+Check the documentation of your database for the correct quote
+characters to use. C<name_sep> needs to be set to allow the SQL
+generator to put the quotes the correct place.
 
-=head3 Deploy update to customers
+In most cases you should set these as part of the arguments passed to 
+L<DBIx::Class::Schema/connect>:
 
-The schema update can be deployed to customers using the same method as before.
+ my $schema = My::Schema->connect(
+  'dbi:mysql:my_db',
+  'db_user',
+  'db_password',
+  {
+    quote_char => '"',
+    name_sep   => '.'
+  }
+ )
 
 =head2 Setting limit dialect for SQL::Abstract::Limit
 
@@ -828,24 +1381,88 @@ to Microsoft SQL-server (See more names in SQL::Abstract::Limit
 The JDBC bridge is one way of getting access to a MSSQL server from a platform
 that Microsoft doesn't deliver native client libraries for. (e.g. Linux)
 
-=head2 Setting quoting for the generated SQL. 
+The limit dialect can also be set at connect time by specifying a 
+C<limit_dialect> key in the final hash as shown above.
 
-If the database contains column names with spaces and/or reserved words, they
-need to be quoted in the SQL queries. This is done using:
+=head2 Working with PostgreSQL array types
 
-  __PACKAGE__->storage->sql_maker->quote_char([ qw/[ ]/] );
-  __PACKAGE__->storage->sql_maker->name_sep('.');
+You can also assign values to PostgreSQL array columns by passing array
+references in the C<\%columns> (C<\%vals>) hashref of the
+L<DBIx::Class::ResultSet/create> and L<DBIx::Class::Row/update> family of
+methods:
 
-The first sets the quote characters. Either a pair of matching
-brackets, or a C<"> or C<'>:
+  $resultset->create({
+    numbers => [1, 2, 3]
+  });
+
+  $row->update(
+    {
+      numbers => [1, 2, 3]
+    },
+    {
+      day => '2008-11-24'
+    }
+  );
+
+In conditions (eg. C<\%cond> in the L<DBIx::Class::ResultSet/search> family of
+methods) you cannot directly use array references (since this is interpreted as
+a list of values to be C<OR>ed), but you can use the following syntax to force
+passing them as bind values:
+
+  $resultset->search(
+    {
+      numbers => \[ '= ?', [numbers => [1, 2, 3]] ]
+    }
+  );
+
+See L<SQL::Abstract/array_datatypes> and L<SQL::Abstract/Literal SQL with
+placeholders and bind values (subqueries)> for more explanation. Note that
+L<DBIx::Class> sets L<SQL::Abstract/bindtype> to C<columns>, so you must pass
+the bind values (the C<[1, 2, 3]> arrayref in the above example) wrapped in
+arrayrefs together with the column name, like this: C<< [column_name => value]
+>>.
+
+=head1 BOOTSTRAPPING/MIGRATING 
+
+=head2 Easy migration from class-based to schema-based setup
+
+You want to start using the schema-based approach to L<DBIx::Class>
+(see L<SchemaIntro.pod>), but have an established class-based setup with lots
+of existing classes that you don't want to move by hand. Try this nifty script
+instead:
+
+  use MyDB;
+  use SQL::Translator;
+  
+  my $schema = MyDB->schema_instance;
+  
+  my $translator           =  SQL::Translator->new( 
+      debug                => $debug          ||  0,
+      trace                => $trace          ||  0,
+      no_comments          => $no_comments    ||  0,
+      show_warnings        => $show_warnings  ||  0,
+      add_drop_table       => $add_drop_table ||  0,
+      validate             => $validate       ||  0,
+      parser_args          => {
+         'DBIx::Schema'    => $schema,
+                              },
+      producer_args   => {
+          'prefix'         => 'My::Schema',
+                         },
+  );
+  
+  $translator->parser('SQL::Translator::Parser::DBIx::Class');
+  $translator->producer('SQL::Translator::Producer::DBIx::Class::File');
+  
+  my $output = $translator->translate(@args) or die
+          "Error: " . $translator->error;
   
-  __PACKAGE__->storage->sql_maker->quote_char('"');
+  print $output;
 
-Check the documentation of your database for the correct quote
-characters to use. C<name_sep> needs to be set to allow the SQL
-generator to put the quotes the correct place.
+You could use L<Module::Find> to search for all subclasses in the MyDB::*
+namespace, which is currently left as an exercise for the reader.
 
-=head2 Overloading methods
+=head1 OVERLOADING METHODS
 
 L<DBIx::Class> uses the L<Class::C3> package, which provides for redispatch of
 method calls, useful for things like default values and triggers. You have to
@@ -853,7 +1470,29 @@ use calls to C<next::method> to overload methods. More information on using
 L<Class::C3> with L<DBIx::Class> can be found in
 L<DBIx::Class::Manual::Component>.
 
-=head3 Changing one field whenever another changes
+=head2 Setting default values for a row
+
+It's as simple as overriding the C<new> method.  Note the use of
+C<next::method>.
+
+  sub new {
+    my ( $class, $attrs ) = @_;
+
+    $attrs->{foo} = 'bar' unless defined $attrs->{foo};
+
+    my $new = $class->next::method($attrs);
+
+    return $new;
+  }
+
+For more information about C<next::method>, look in the L<Class::C3> 
+documentation. See also L<DBIx::Class::Manual::Component> for more
+ways to write your own base classes to do this.
+
+People looking for ways to do "triggers" with DBIx::Class are probably
+just looking for this. 
+
+=head2 Changing one field whenever another changes
 
 For example, say that you have three columns, C<id>, C<number>, and 
 C<squared>.  You would like to make changes to C<number> and have
@@ -871,7 +1510,7 @@ You can accomplish this by overriding C<store_column>:
 Note that the hard work is done by the call to C<next::method>, which
 redispatches your call to store_column in the superclass(es).
 
-=head3 Automatically creating related objects
+=head2 Automatically creating related objects
 
 You might have a class C<Artist> which has many C<CD>s.  Further, if you
 want to create a C<CD> object every time you insert an C<Artist> object.
@@ -887,7 +1526,50 @@ You can accomplish this by overriding C<insert> on your objects:
 where C<fill_from_artist> is a method you specify in C<CD> which sets
 values in C<CD> based on the data in the C<Artist> object you pass in.
 
-=head2 Debugging DBIx::Class objects with Data::Dumper
+=head2 Wrapping/overloading a column accessor
+
+B<Problem:>
+
+Say you have a table "Camera" and want to associate a description
+with each camera. For most cameras, you'll be able to generate the description from
+the other columns. However, in a few special cases you may want to associate a
+custom description with a camera.
+
+B<Solution:>
+
+In your database schema, define a description field in the "Camera" table that
+can contain text and null values.
+
+In DBIC, we'll overload the column accessor to provide a sane default if no
+custom description is defined. The accessor will either return or generate the
+description, depending on whether the field is null or not.
+
+First, in your "Camera" schema class, define the description field as follows:
+
+  __PACKAGE__->add_columns(description => { accessor => '_description' });
+
+Next, we'll define the accessor-wrapper subroutine:
+
+  sub description {
+      my $self = shift;
+
+      # If there is an update to the column, we'll let the original accessor
+      # deal with it.
+      return $self->_description(@_) if @_;
+
+      # Fetch the column value.
+      my $description = $self->_description;
+
+      # If there's something in the description field, then just return that.
+      return $description if defined $description && length $descripton;
+
+      # Otherwise, generate a description.
+      return $self->generate_description;
+  }
+
+=head1 DEBUGGING AND PROFILING
+
+=head2 DBIx::Class objects with Data::Dumper
 
 L<Data::Dumper> can be a very useful tool for debugging, but sometimes it can
 be hard to find the pertinent data in all the data it can generate.
@@ -931,17 +1613,6 @@ base class and set C<$Data::Dumper::Freezer> to its name and L<Data::Dumper>
 will automagically clean up your data before printing it. See
 L<Data::Dumper/EXAMPLES> for more information.
 
-=head2 Retrieving a row object's Schema
-
-It is possible to get a Schema object from a row object like so:
-
-  my $schema = $cd->result_source->schema;
-  # use the schema as normal:
-  my $artist_rs = $schema->resultset('Artist'); 
-
-This can be useful when you don't want to pass around a Schema object to every
-method.
-
 =head2 Profiling
 
 When you enable L<DBIx::Class::Storage>'s debugging it prints the SQL
@@ -964,7 +1635,7 @@ mechanism:
     my $sql = shift();
     my $params = @_;
 
-    print "Executing $sql: ".join(', ', @params)."\n";
+    $self->print("Executing $sql: ".join(', ', @params)."\n");
     $start = time();
   }
 
@@ -973,7 +1644,8 @@ mechanism:
     my $sql = shift();
     my @params = @_;
 
-    printf("Execution took %0.4f seconds.\n", time() - $start);
+    my $elapsed = sprintf("%0.4f", time() - $start);
+    $self->print("Execution took $elapsed seconds.\n");
     $start = undef;
   }
 
@@ -981,8 +1653,8 @@ mechanism:
 
 You can then install that class as the debugging object:
 
-  __PACKAGE__->storage()->debugobj(new My::Profiler());
-  __PACKAGE__->storage()->debug(1);
+  __PACKAGE__->storage->debugobj(new My::Profiler());
+  __PACKAGE__->storage->debug(1);
 
 A more complicated example might involve storing each execution of SQL in an
 array:
@@ -1001,219 +1673,98 @@ array:
 
 You could then create average, high and low execution times for an SQL
 statement and dig down to see if certain parameters cause aberrant behavior.
+You might want to check out L<DBIx::Class::QueryLog> as well.
 
-=head2 Getting the value of the primary key for the last database insert
-
-AKA getting last_insert_id
+=head1 STARTUP SPEED
 
-If you are using PK::Auto, this is straightforward:
+L<DBIx::Class|DBIx::Class> programs can have a significant startup delay
+as the ORM loads all the relevant classes. This section examines
+techniques for reducing the startup delay.
 
-  my $foo = $rs->create(\%blah);
-  # do more stuff
-  my $id = $foo->id; # foo->my_primary_key_field will also work.
+These tips are are listed in order of decreasing effectiveness - so the
+first tip, if applicable, should have the greatest effect on your
+application.
 
-If you are not using autoincrementing primary keys, this will probably
-not work, but then you already know the value of the last primary key anyway.
+=head2 Statically Define Your Schema
 
-=head2 Dynamic Sub-classing DBIx::Class proxy classes 
-(AKA multi-class object inflation from one table) 
- 
-L<DBIx::Class> classes are proxy classes, therefore some different
-techniques need to be employed for more than basic subclassing.  In
-this example we have a single user table that carries a boolean bit
-for admin.  We would like like to give the admin users
-objects(L<DBIx::Class::Row>) the same methods as a regular user but
-also special admin only methods.  It doesn't make sense to create two
-seperate proxy-class files for this.  We would be copying all the user
-methods into the Admin class.  There is a cleaner way to accomplish
-this.
+If you are using
+L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to build the
+classes dynamically based on the database schema then there will be a
+significant startup delay.
 
-Overriding the C<inflate_result> method within the User proxy-class
-gives us the effect we want.  This method is called by
-L<DBIx::Class::ResultSet> when inflating a result from storage.  So we
-grab the object being returned, inspect the values we are looking for,
-bless it if it's an admin object, and then return it.  See the example
-below:
- 
-B<Schema Definition> 
- 
-    package DB::Schema; 
-     
-    use base qw/DBIx::Class::Schema/; 
- 
-    __PACKAGE__->load_classes(qw/User/); 
- 
- 
-B<Proxy-Class definitions> 
- 
-    package DB::Schema::User; 
-     
-    use strict; 
-    use warnings; 
-    use base qw/DBIx::Class/; 
-     
-    ### Defined what our admin class is for ensure_class_loaded 
-    my $admin_class = __PACKAGE__ . '::Admin'; 
-     
-    __PACKAGE__->load_components(qw/Core/); 
-     
-    __PACKAGE__->table('users'); 
-     
-    __PACKAGE__->add_columns(qw/user_id   email    password  
-                                firstname lastname active 
-                                admin/); 
-     
-    __PACKAGE__->set_primary_key('user_id'); 
-     
-    sub inflate_result { 
-        my $self = shift;  
-        my $ret = $self->next::method(@_); 
-        if( $ret->admin ) {### If this is an admin rebless for extra functions  
-            $self->ensure_class_loaded( $admin_class ); 
-            bless $ret, $admin_class; 
-        } 
-        return $ret; 
-    } 
-     
-    sub hello { 
-        print "I am a regular user.\n"; 
-        return ; 
-    } 
-     
-     
-    package DB::Schema::User::Admin; 
-     
-    use strict; 
-    use warnings; 
-    use base qw/DB::Schema::User/; 
-     
-    sub hello 
-    { 
-        print "I am an admin.\n"; 
-        return; 
-    } 
-     
-    sub do_admin_stuff 
-    { 
-        print "I am doing admin stuff\n"; 
-        return ; 
-    } 
- 
-B<Test File> test.pl 
- 
-    use warnings; 
-    use strict; 
-    use DB::Schema; 
-     
-    my $user_data = { email    => 'someguy@place.com',  
-                      password => 'pass1',  
-                      admin    => 0 }; 
-                           
-    my $admin_data = { email    => 'someadmin@adminplace.com',  
-                       password => 'pass2',  
-                       admin    => 1 }; 
-                           
-    my $schema = DB::Schema->connection('dbi:Pg:dbname=test'); 
-     
-    $schema->resultset('User')->create( $user_data ); 
-    $schema->resultset('User')->create( $admin_data ); 
-     
-    ### Now we search for them 
-    my $user = $schema->resultset('User')->single( $user_data ); 
-    my $admin = $schema->resultset('User')->single( $admin_data ); 
-     
-    print ref $user, "\n"; 
-    print ref $admin, "\n"; 
-     
-    print $user->password , "\n"; # pass1 
-    print $admin->password , "\n";# pass2; inherited from User 
-    print $user->hello , "\n";# I am a regular user. 
-    print $admin->hello, "\n";# I am an admin. 
- 
-    ### The statement below will NOT print 
-    print "I can do admin stuff\n" if $user->can('do_admin_stuff'); 
-    ### The statement below will print 
-    print "I can do admin stuff\n" if $admin->can('do_admin_stuff'); 
+For production use a statically defined schema (which can be generated
+using L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to dump
+the database schema once - see
+L<make_schema_at|DBIx::Class::Schema::Loader/make_schema_at> and
+L<dump_directory|DBIx::Class::Schema::Loader/dump_directory> for more
+details on creating static schemas from a database).
 
-=head2 Skip object creation for faster results
+=head2 Move Common Startup into a Base Class
 
-DBIx::Class is not built for speed, it's built for convenience and
-ease of use, but sometimes you just need to get the data, and skip the
-fancy objects.
-  
-To do this simply use L<DBIx::Class::ResultClass::HashRefInflator>.
-  
- my $rs = $schema->resultset('CD');
- 
- $rs->result_class('DBIx::Class::ResultClass::HashRefInflator');
- 
- my $hash_ref = $rs->find(1);
-  
-Wasn't that easy?
-  
-=head2 Get raw data for blindingly fast results
+Typically L<DBIx::Class> result classes start off with
 
-If the C<inflate_result> solution above is not fast enough for you, you
-can use a DBIx::Class to return values exactly as they come out of the
-data base with none of the convenience methods wrapped round them.
+    use base qw/DBIx::Class/;
+    __PACKAGE__->load_components(qw/InflateColumn::DateTime Core/);
 
-This is used like so:-
+If this preamble is moved into a common base class:-
 
-  my $cursor = $rs->cursor
-  while (my @vals = $cursor->next) {
-      # use $val[0..n] here
-  }
+    package MyDBICbase;
+    
+    use base qw/DBIx::Class/;
+    __PACKAGE__->load_components(qw/InflateColumn::DateTime Core/);
+    1;
 
-You will need to map the array offsets to particular columns (you can
-use the I<select> attribute of C<search()> to force ordering).
+and each result class then uses this as a base:-
 
-=head2 Want to know if find_or_create found or created a row?
+    use base qw/MyDBICbase/;
 
-Just use C<find_or_new> instead, then check C<in_storage>:
+then the load_components is only performed once, which can result in a
+considerable startup speedup for schemas with many classes.
 
-  my $obj = $rs->find_or_new({ blah => 'blarg' });
-  unless ($obj->in_storage) {
-    $obj->insert;
-    # do whatever else you wanted if it was a new row
-  }
+=head2 Explicitly List Schema Result Classes
 
-=head3 Wrapping/overloading a column accessor
+The schema class will normally contain
 
-Problem: Say you have a table "Camera" and want to associate a description
-with each camera. For most cameras, you'll be able to generate the description from
-the other columns. However, in a few special cases you may want to associate a
-custom description with a camera.
+    __PACKAGE__->load_classes();
 
-Solution:
+to load the result classes. This will use L<Module::Find|Module::Find>
+to find and load the appropriate modules. Explicitly defining the
+classes you wish to load will remove the overhead of
+L<Module::Find|Module::Find> and the related directory operations:-
 
-In your database schema, define a description field in the "Camera" table that
-can contain text and null values.
+    __PACKAGE__->load_classes(qw/ CD Artist Track /);
 
-In DBIC, we'll overload the column accessor to provide a sane default if no
-custom description is defined. The accessor will either return or generate the
-description, depending on whether the field is null or not.
+If you are instead using the L<load_namespaces|DBIx::Class::Schema/load_namespaces>
+syntax to load the appropriate classes there is not a direct alternative
+avoiding L<Module::Find|Module::Find>.
 
-First, in your "Camera" schema class, define the description field as follows:
+=head1 MEMORY USAGE
 
-  __PACKAGE__->add_columns(description => { accessor => '_description' });
+=head2 Cached statements
 
-Next, we'll define the accessor-wrapper subroutine:
+L<DBIx::Class> normally caches all statements with L<< prepare_cached()|DBI/prepare_cached >>.
+This is normally a good idea, but if too many statements are cached, the database may use too much
+memory and may eventually run out and fail entirely.  If you suspect this may be the case, you may want
+to examine DBI's L<< CachedKids|DBI/CachedKidsCachedKids_(hash_ref) >> hash:
 
-  sub description {
-      my $self = shift;
+    # print all currently cached prepared statements
+    print for keys %{$schema->storage->dbh->{CachedKids}};
+    # get a count of currently cached prepared statements
+    my $count = scalar keys %{$schema->storage->dbh->{CachedKids}};
 
-      # If there is an update to the column, we'll let the original accessor
-      # deal with it.
-      return $self->_description(@_) if @_;
+If it's appropriate, you can simply clear these statements, automatically deallocating them in the
+database:
 
-      # Fetch the column value.
-      my $description = $self->_description;
+    my $kids = $schema->storage->dbh->{CachedKids};
+    delete @{$kids}{keys %$kids} if scalar keys %$kids > 100;
 
-      # If there's something in the description field, then just return that.
-      return $description if defined $description && length $descripton;
+But what you probably want is to expire unused statements and not those that are used frequently.
+You can accomplish this with L<Tie::Cache> or L<Tie::Cache::LRU>:
 
-      # Otherwise, generate a description.
-      return $self->generate_description;
-  }
+    use Tie::Cache;
+    use DB::Main;
+    my $schema = DB::Main->connect($dbi_dsn, $user, $pass, {
+        on_connect_do => sub { tie %{shift->_dbh->{CachedKids}}, 'Tie::Cache', 100 },
+    });
 
 =cut