ALTER TABLE `vn2008`.`Colas` 
DROP FOREIGN KEY `Colas_ibfk_1`,
DROP FOREIGN KEY `Colas_ibfk_2`,
DROP FOREIGN KEY `Colas_ibfk_3`,
DROP FOREIGN KEY `Colas_ibfk_5`;
ALTER TABLE `vn2008`.`Colas` 
CHANGE COLUMN `Id_Impresora` `Id_Impresora` TINYINT(3) UNSIGNED NULL DEFAULT NULL ,
CHANGE COLUMN `Id_Prioridad` `Id_Prioridad` TINYINT(3) UNSIGNED NULL DEFAULT NULL ;
ALTER TABLE `vn2008`.`Colas` 
ADD CONSTRAINT `Colas_ibfk_4`
  FOREIGN KEY (`Id_Impresora`)
  REFERENCES `vn2008`.`Impresoras` (`Id_Impresora`)
  ON UPDATE CASCADE,
ADD CONSTRAINT `Colas_ibfk_3`
  FOREIGN KEY (`Id_Prioridad`)
  REFERENCES `vn2008`.`Prioridades` (`Id_Prioridad`)
  ON UPDATE CASCADE;