Trigger Definitions

Triggers are a convenient programming abstraction activated at transaction commit based on updates to the base tables. All trigger definitions are considered together at the transaction commit. There is no a priori defined order in which they run. Each may in turn activate new triggers, but each trigger definition is also executed only once per transaction commit.

trigger_def: CREATE [ OR REPLACE ] TRIGGER qname  trigger_action_time  trigger_event  ON  ident  opt_referencing_list  triggered_action

trigger_action_time: BEFORE | AFTER

trigger_event: INSERT | DELETE | TRUNCATE | UPDATE | UPDATE OF ident ','...

opt_referencing_list: [ REFERENCING old_or_new_values_alias ... ]

      OLD [ ROW ] [ AS ] ident
    | NEW [ ROW ] [ AS ] ident
    | OLD TABLE [ AS ] ident
    | NEW TABLE [ AS ] ident

     opt_for_each [ WHEN search_condition ] triggered_statement

opt_for_each: /* default is for each statement */ | FOR EACH ROW | FOR EACH STATEMENT

   | BEGIN ATOMIC trigger_procedure_statement_list END

   | declare_statement
   | set_statement
   | control_statement
   | select_statement_single_row

Note: FOR EACH STATEMENT is the default if not specified.
The option to specify a schema name for the trigger name has been removed. Previous the schema name of a full qualified trigger name already had to be the same as the schema name of the table.


create table t1 (id int, name varchar(1024));
--test FOR EACH STATEMENT (default one)
insert into t1 values(10, 'monetdb');
insert into t1 values(20, 'monet');

create trigger test5
after update on t1 referencing new row as new_row
for each statement
when ( > 0) insert into t1 values(4, 'update_when_statement_true');