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CREATE TRIGGER
statement and does not include the optional column list, then any UPDATE on the table will
activate the trigger.
ON table_name
Identifies the name of the table where the trigger is defined. A triggering statement that
specifies table_name causes the trigger to execute. table_name cannot be the name of a
view.
REFERENCING OLDROW [ , NEWROW ] | NEWROW [ , OLDROW ]
Provides a mechanism for SQL to pass row values as input parameters to the stored
procedure implemented by java_snippet. The code in java_snippet uses the getValue
method of the NEWROW and OLDROW objects to retrieve values of columns in rows affected
by the trigger event and store them in procedure variables. This clause is allowed only if
the trigger specifies the FOR EACH ROW clause.
The meaning of the OLDROW and NEWROW arguments of the REFERENCING clause depends on
whether the trigger event is INSERT, UPDATE, or DELETE. For example:
• INSERT...REFERENCING NEWROW means the triggered action can access values of
columns of each row inserted. SQL passes the column values specified by the INSERT
statement.
• INSERT...REFERENCING OLDROW is meaningless, since there are no existing values for
a row being inserted. INSERT...REFERENCING OLDROW generates a syntax error.
• UPDATE...REFERENCING OLDROW means the triggered action can access the values of
columns, before they are changed, of each row updated. SQL passes the column
values of the row as it exists in the database before the update operation.
• DELETE...REFERENCING OLDROW means the triggered action can access values of
columns of each row deleted. SQL passes the column values of the row as it exists
in the database before the delete operation.
• DELETE...REFERENCING NEWROW is meaningless, since there are no new existing values
to pass for a row being deleted. DELETE...REFERENCING OLDROW generates a syntax
error.
• UPDATE is the only triggering statement that allows both NEWROW and OLDROW in the
REFERENCING clause.
• UPDATE...REFERENCING NEWROW means the triggered action can access the values of
columns, after they are changed, of each row updated. SQL passes the column values
specified by the UPDATE statement.
• The trigger action time (BEFORE or AFTER) does not affect the meaning of the
REFERENCING clause. For instance, BEFORE UPDATE...REFERENCING NEWROW still means
the values of columns after they are updated will be available to the triggered action.
• The REFERENCING clause generates an error if the trigger does not include the FOR
EACH ROW clause.
FOR EACH { ROW | STATEMENT }
Controls the execution frequency of the triggered action implemented by java_snippet.
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