ALTER TABLE `vn2008`.`Facturas` 
DROP FOREIGN KEY `invoice_bank_id`;
ALTER TABLE `vn2008`.`Facturas` 
CHANGE COLUMN `Id_Banco` `Id_Banco` INT(11) NULL DEFAULT NULL ;
ALTER TABLE `vn2008`.`Facturas` 
ADD CONSTRAINT `invoice_bank_id`
  FOREIGN KEY (`Id_Banco`)
  REFERENCES `vn2008`.`Bancos` (`Id_Banco`)
  ON UPDATE CASCADE;