Specify the trigger event

The trigger event is the type of DML statement that activates the trigger. When a statement of this type is performed on the table, the database server executes the SQL statements that make up the triggered action. For tables, the trigger event can be an INSERT, SELECT, DELETE, or UPDATE statement. For UPDATE or SELECT trigger event, you can specify one or more columns in the table to activate the trigger. If you do not specify any columns, then an UPDATE or SELECT of any column in the table activates the trigger. You can define multiple INSERT, DELETE, UPDATE and SELECT triggers on the same table, and multiple INSERT, DELETE, and UPDATE triggers on the same view.

You can only create a trigger on a table or view in the current database. Triggers cannot reference a remote table or view.

In the following excerpt from a CREATE TRIGGER statement, the trigger event is defined as an update of the quantity column in the items table:

CREATE TRIGGER upqty
   UPDATE OF quantity ON items     -- an UPDATE trigger event

This portion of the statement identifies the table on which you define the trigger. If the trigger event is an insert or delete operation, only the type of statement and the table name are required, as the following example shows:

CREATE TRIGGER ins_qty
   INSERT ON items                  -- an INSERT trigger event