The trigger defines events that happen when some other event, called a triggering event, occurs. This database object is essentially a stored SQL statement associated with a table called a subject table.
Teradata Database implementation of triggers complies with ANSI SQL specifications and provides extensions.
Triggers execute when any of the following modifies a specified column or columns in the subject table:
Typically, the stored SQL statements perform a DELETE, INSERT, UPDATE, or MERGE on a table different from the subject table.