create trigger statement ::=
CREATE TRIGGER [owner_name.]trigname
{ BEFORE | AFTER }
  { INSERT | DELETE | UPDATE [ OF column_name[ , ...]}
ON table_name[ REFERENCING { OLDROW [, NEWROW ]| NEWROW [, OLDROW ]}]
[ FOR EACH { ROW | STATEMENT }][ IMPORT
java_import_clause]
BEGIN
java_snippet
END