Function create_set_null_trg

src/gpre/cmd.cpp:1036–1122

//

static void create_set_null_trg(gpre_req* request,
								const act* action,
								cnstrt* constraint,
								bool on_upd_trg)
{
	gpre_lls* for_key_fld = constraint->cnstrt_fields;
	const gpre_rel* relation = (gpre_rel*) action->act_object;

	// no trigger name. It is generated by the engine
	put_string(request, isc_dyn_def_trigger, "", (USHORT) 0);

	put_numeric(request, isc_dyn_trg_type,
				(SSHORT) (on_upd_trg ? POST_MODIFY_TRIGGER : POST_ERASE_TRIGGER));

	request->add_byte(isc_dyn_sql_object);
	put_numeric(request, isc_dyn_trg_sequence, (SSHORT) 1);
	put_numeric(request, isc_dyn_trg_inactive, (SSHORT) 0);
	put_cstring(request, isc_dyn_rel_name, constraint->cnstrt_referred_rel->str_string);

	// the trigger blr

	request->add_byte(isc_dyn_trg_blr);
	const USHORT offset = request->req_blr - request->req_base;

	request->add_word(0);
	if (request->req_flags & REQ_blr_version4)
		request->add_byte(blr_version4);
	else
		request->add_byte(blr_version5);

	// for ON UPDATE TRIGGER only: generate the trigger firing condition:
	// if prim_key.old_value != prim_key.new value.
	// Note that the key could consist of multiple columns

	if (on_upd_trg)
	{
		create_trg_firing_cond(request, constraint);
		request->add_byte(blr_begin);
		request->add_byte(blr_begin);
	}

	request->add_byte(blr_for);
	request->add_byte(blr_rse);

	// the context for the prim. key relation
	request->add_byte(1);

	request->add_byte(blr_relation);
	put_cstring(request, 0, relation->rel_symbol->sym_string);
	// the context for the foreign key relation
	request->add_byte(2);

	create_matching_blr(request, constraint);

	request->add_byte(blr_modify);
	request->add_byte((SSHORT) 2);
	request->add_byte((SSHORT) 2);
	request->add_byte(blr_begin);