16.20 - Trigger Terminology - Teradata Database - Teradata Vantage NewSQL Engine

Teradata Vantage™ SQL Data Definition Language Detailed Topics

Product
Teradata Database
Teradata Vantage NewSQL Engine
Release Number
16.20
Release Date
March 2019
Content Type
Programming Reference
Publication ID
B035-1184-162K
Language
English (United States)

The following table defines terms associated with the creation and use of an SQL trigger:

Term Description
DISABLED An optional element of a trigger definition that defines the current state of the trigger.

A disabled trigger is inactive until it is enabled, but its definition remains in the data dictionary.

ENABLED An optional element of a trigger definition that defines the current state of the trigger.

An enabled trigger is an active database object.

ORDER clause An optional clause that assigns an integer value to determine the order of execution of the trigger when multiple triggers having the same trigger action time and trigger event are defined on the same table.
REFERENCING clause An optional clause that allows the WHEN condition and triggered actions of a trigger to reference the set of rows in the transition table set.

See REFERENCING Clause.

Subject table The table with which a trigger is associated and on which its triggering event takes place.
Transition row A row in the transition table.
Transition table A temporary table that contains either old or new values, or both, for rows modified by a triggering statement.

See Transition Tables for more information about transition tables.

Trigger action time A specification that indicates when triggered SQL statements perform in relation to the triggering event.

A triggered statement performs either BEFORE or AFTER a triggering event.

Trigger granularity A specification that indicates whether the trigger performs for each row or for each statement modified by the triggering event.

Trigger granularity is expressed as the trigger type, either FOR EACH STATEMENT or FOR EACH ROW.

FOR EACH STATEMENT is the default granularity for all triggers.

Triggered action The main action part of the trigger definition, consisting of the following elements:
  • An optional trigger granularity clause
  • An optional WHEN condition
  • A triggered SQL statement
Triggered SQL statement A set of SQL statements fired by the triggering event.

A triggered SQL statement can modify one or more tables, including the subject table.

Triggering event The DML statement whose execution fires the trigger. This is a DELETE, INSERT, or UPDATE operation or a variation of these operations. An UPDATE operation can have a list of columns associated with it.
WHEN condition A Boolean search condition that defines different things for different trigger types.
  • For a Statement trigger, the WHEN condition determines whether the trigger executes.
  • For a Row trigger, the WHEN condition determines the set of changed rows for which the trigger executes.