DBIx::Class::Manual::SQLHackers::DELETE - DBIx::Class for SQL Hackers - DELETE
DELETE FROM users WHERE id = 1;
The simplest form of delete removes a single row from a table using the primary key value. We find the row, then call the delete method on it. delete can be called on any result row object.
my $schema = MyDatabase::Schema->connect('dbi:SQLite:my.db');
my $fred_user = $schema->resultset('User')->find({ id => 1 });
$fred_user->delete;
This can also be done as one statement, skipping the extra temporary variable, if it is not needed later:
$schema->resultset('User')->find({ id => 1 })->delete;
In the first variant, the $fred_user row object will still contain the last known contents of Fred's data. A call to $fred_user->in_storage will return false (0), showing that the row object is no longer connected to a actual database row.
DELETE FROM posts WHERE created_date <= '2000-01-01';
Use a ResultSet to define the WHERE clause using search, then call the delete method on it directly.
my $old_posts = $schema->resultset('Post')->search({ created_date => { '<=' => '2000-01-01' }, });
$old_posts->delete;
Unlike the single row deletion above, the contents of the rows to be deleted are never fetched from the database, so no record of them now remains.
NOTE: Calling delete on a ResultSet object will not run any overridden delete methods in your Result Classes or any loaded Components. To force these to run, call delete_all instead:
$old_posts->delete_all();
This will also issue a separate delete statement for each row to be removed.
DELETE FROM users WHERE id = 1; DELETE FROM comments WHERE user_id = 1;
Cascading deletes ensure the integrity of your data, if a User row is removed, then any items belonging to that user (for example comments created by the user), should also be removed.
NOTE: This is a rather drastic action, to prevent problems in your application, consider de-activating accounts instead of removing them!
For the time being DBIx::Class defaults to cascade deletion for the following types of relationships: has_many, has_one, might_have. That is, it will automatically issue the above statements. It is recommended not to rely on this implicit behavior, as it will be deprecated in a later version of DBIC. Instead declare proper cascading constraints in your RDBMS as described in "Table creation with references" in DBIx::Class::Manual::SQLHackers::CREATE.
If your database is already properly set up to cascade deletes for you, you can noop DBIx::Class' extra cascading statements:
__PACKAGE__->has_many('posts', 'MyDatabase::Schema::Result::Post', 'user_id', { cascade_delete => 0 });
To install DBIx::Class::Manual::SQLHackers::DELETE, copy and paste the appropriate command in to your terminal.
cpanm
cpanm DBIx::Class::Manual::SQLHackers::DELETE
CPAN shell
perl -MCPAN -e shell install DBIx::Class::Manual::SQLHackers::DELETE
For more information on module installation, please visit the detailed CPAN module installation guide.