Triggers and Identity Columns
The following rules and restrictions apply to triggers and INSERT operations into
tables with identity columns.
You cannot create a trigger definition if its triggering statement is an INSERT on
a subject table that has an identity column and its triggered action statement or
WHEN condition references that column.If a triggered statement makes row references to the table that is involved in the
triggering statement, and the triggered statement is an INSERT operation into a table
with a GENERATED ALWAYS identity column, Teradata Database substitutes a dummy value
for the USING value for the referenced row and then generates the actual identity
column number in the Dispatcher before sending it to its destination AMP.