15.00 - Trigger Support for Unity Director - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

prodname
Teradata Database
vrm_release
15.00
category
Programming Reference
featnum
B035-1184-015K

Trigger Support for Unity Director

Unity Director sends request-specific context information as part of a request that executes a trigger to enable Teradata Database to change the result of the executed trigger indirectly by substituting a value predefined by Unity Director for a non‑deterministic result. Teradata Database makes this context information available to a trigger when it is executed from the default connection for the session.

Consider, for example, the following table and trigger definitions, where Unity Director overrides the RANDOM functions specified in the select lists of the triggered INSERT … SELECT requests specified in the trigger definitions.

     CREATE TABLE t1 (
       a INTEGER, 
       b INTEGER) 
     PRIMARY INDEX (a);
 
     CREATE TABLE t2 (
       a INTEGER,
       b INTEGER) 
     PRIMARY INDEX (a);
 
     CREATE TABLE t3 (
       a INTEGER,
       b INTEGER) 
     PRIMARY INDEX(a);
 
     CREATE TRIGGER trigt1 
       AFTER INSERT ON t1 (
         INSERT t2 
           SELECT a, RANDOM(200, 300)+1 
           FROM t1;);
 
     CREATE TRIGGER trigt2 
       AFTER INSERT ON t2 (
         INSERT t3 
           SELECT a, RANDOM(200, 300)+1 
           FROM t2;);