15.00 - Trigger Support for Unity Director - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

Teradata Database
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Programming Reference
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English (United States)

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) 
     CREATE TABLE t2 (
       a INTEGER,
       b INTEGER) 
     CREATE TABLE t3 (
       a INTEGER,
       b INTEGER) 
     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;);