###Eliminar-Crear index con llave foranea
~~~
ALTER TABLE ut_cfd DROP FOREIGN KEY RLCFDufIVenta_VentaSys_PK;
DROP INDEX uf_IVenta ON ut_cfd;

INDEX RLCFDufCFDFolio_CFDFolioSys_PK (uf_CFDFolio),
CONSTRAINT xRLCFDufCFDFolio_CFDFolioSys_PK FOREIGN KEY (uf_CFDFolio)

INDEX RLCFDufIVenta_VentaSys_PK (uf_IVenta),
ADD CONSTRAINT RLCFDufIVenta_VentaSys_PK FOREIGN KEY (uf_IVenta) REFERENCES venta(Sys_PK) ON DELETE ESTRICT ON UPDATE RESTRICT

ALTER TABLE ut_cfd ADD INDEX (uf_IVenta);

alter table ut_cfd ADD CONSTRAINT RLCFDufIVenta_VentaSys_PK FOREIGN KEY (uf_IVenta) REFERENCES venta(Sys_PK) ON DELETE ESTRICT ON UPDATE RESTRICT;
~~~