=item .. tell DBIx::Class about relationships between my tables?
-There are a vareity of relationship types that come pre-defined for
+There are a variety of relationship types that come pre-defined for
you to use. These are all listed in L<DBIx::Class::Relationship>. If
you need a non-standard type, or more information, look in
L<DBIx::Class::Relationship::Base>.
Read the documentation on L<DBIx::Class::Relationship/many_to_many>.
-=item .. stop DBIx::Class from attempting to cascade deletes on my has_many relationships?
+=item .. stop DBIx::Class from attempting to cascade deletes on my has_many and might_have relationships?
By default, DBIx::Class cascades deletes and updates across
-C<has_many> relationships. If your database already does this (and
-that is probably better), turn it off by supplying C<< cascade_delete => 0 >>
-in the relationship attributes. See L<DBIx::Class::Relationship::Base>.
+C<has_many> and C<might_have> relationships. You can disable this
+behaviour on a per-relationship basis by supplying
+C<< cascade_delete => 0 >> in the relationship attributes.
+
+The cascaded operations are performed after the requested delete or
+update, so if your database has a constraint on the relationship, it
+will have deleted/updated the related records or raised an exception
+before DBIx::Class gets to perform the cascaded operation.
+
+See L<DBIx::Class::Relationship>.
=item .. use a relationship?
my $interval = "now() - interval '12 hours'";
->search({last_attempt => { '<' => \$interval } })
+=item .. search with an SQL function on the left hand side?
+
+To use an SQL function on the left hand side of a comparison:
+
+ ->search({}, { where => \'YEAR(date_of_birth)=1979' });
+
+=begin hidden
+
+(When the bind arg ordering bug is fixed, the previous example can be
+replaced with the following.)
+
+ ->search({}, { where => \'YEAR(date_of_birth)=?', bind => [ 1979 ] });
+
+=end hidden
+
+Or, if you have quoting off:
+
+ ->search({ 'YEAR(date_of_birth' => 1979 });
+
=item .. find more help on constructing searches?
Behind the scenes, DBIx::Class uses L<SQL::Abstract> to help construct
L<DBIx::Class::Manual::Cookbook>, try looking in the SQL::Abstract
documentation.
+=item .. make searches in Oracle (10gR2 and newer) case-insensitive?
+
+To make Oracle behave like most RDBMS use on_connect_do to issue
+alter session statements on database connection establishment:
+
+ ->on_connect_do("ALTER SESSION SET NLS_COMP = 'LINGUISTIC'");
+ ->on_connect_do("ALTER SESSION SET NLS_SORT = '<NLS>_CI'");
+ e.g.
+ ->on_connect_do("ALTER SESSION SET NLS_SORT = 'BINARY_CI'");
+ ->on_connect_do("ALTER SESSION SET NLS_SORT = 'GERMAN_CI'");
+
+
=back
=head2 Fetching data
Then call L<DBIx::Class::ResultSet/slice> and ask it only to return 1 row:
- ->slice(0,1)
+ ->slice(0)
These two calls can be combined into a single statement:
- ->search->(undef, { order_by => "id DESC" })->slice(0,1)
+ ->search->(undef, { order_by => "id DESC" })->slice(0)
Why slice instead of L<DBIx::Class::ResultSet/first> or L<DBIx::Class::ResultSet/single>?
If supported by the database, slice will use LIMIT/OFFSET to hint to the database that we
inserted key, you can tell it the name of the sequence in the
C<column_info> supplied with C<add_columns>.
- ->add_columns({ id => { sequence => 'mysequence' } });
+ ->add_columns({ id => { sequence => 'mysequence', auto_nextval => 1 } });
=item .. insert many rows of data efficiently?
->update({ somecolumn => \'othercolumn' })
+But note that when using a scalar reference the column in the database
+will be updated but when you read the value from the object with e.g.
+
+ ->somecolumn()
+
+you still get back the scalar reference to the string, B<not> the new
+value in the database. To get that you must refresh the row from storage
+using C<discard_changes()>. Or chain your function calls like this:
+
+ ->update->discard_changes
+
+ to update the database and refresh the object in one step.
+
=item .. store JSON/YAML in a column and have it deflate/inflate automatically?
You can use L<DBIx::Class::InflateColumn> to accomplish YAML/JSON storage transparently.
search again or relationship accessors. The SQL query is only run when
you ask the resultset for an actual row object.
+=item How do I deal with tables that lack a primary key?
+
+If your table lacks a primary key, DBIx::Class can't work out which row
+it should operate on, for example to delete or update. However, a
+UNIQUE constraint on one or more columns allows DBIx::Class to uniquely
+identify the row, so you can tell L<DBIx::Class::ResultSource> these
+columns act as a primary key, even if they don't from the database's
+point of view:
+
+ $resultset->set_primary_key(@column);
+
=back
=head2 Notes for CDBI users
projects / dbsrgits/DBIx-Class.git / blobdiff