declare
    object_exists exception;
    pragma exception_init (object_exists , -00955);
begin
	execute immediate 'ALTER TABLE TARIFA_MINIMA ADD (COEFICIENTETARIFA_ID NUMBER(7) )';	
    exception when others then null;
end;
/

declare
    object_exists exception;
    pragma exception_init (object_exists , -00955);
begin
	execute immediate 'ALTER TABLE TARIFA_MINIMA ADD CONSTRAINT TARIFA_MINIMA_FK_COEFICIENTE FOREIGN KEY (COEFICIENTETARIFA_ID) REFERENCES COEFICIENTE_TARIFA (COEFICIENTETARIFA_ID) ENABLE';	
    exception when others then null;
end;