SELECT GEN_ID(ID_HEDER,0)+1 FROM ANY_TABLE INTO :ID;
INSERT INTO INVOICE_HEADER (No,Date_of,Etc) VALUES ('122','2013-10-20','Any text')
/* ID record of INVOICE_HEADER table gets the ID_number from the generator above. So
now we have to check if the ID =GEN_ID(ID_HEADER,0) */
IF (ID=GEN_ID(ID_HEADER,0)) THEN
BEGIN
INSERT INTO INVOICE_FOOTER (RELACION_ID, TEXT, Etc) Values (ID, 'Text', Etc);
END
ELSE
REVERT TRANSACTION
Это все