A.ALTER TABLE table_name DROP CONSTRAINT constraint_name CASCADE B.ALTER TABLE table_name DROP CONSTRAINT FOREIGN KEY CASCADE C.DROP CONSTRAINT table_name(constraint_name) D.ALTER TABLE table_name DROP CONSTRAINT constraint_name
A.ALTER TABLE雇員MODIFY COLUMN dept_id_fk FOREIGN KEY(部門(mén)標(biāo)識(shí))REFERENCES部門(mén)(部門(mén)標(biāo)識(shí)) B.ALTER TABLE雇員ADD CONSTRAINT dept_id_fk FOREIGNKEY(部門(mén)標(biāo)識(shí))REFERENCES部門(mén)(部門(mén)標(biāo)識(shí)) C.ALTER TABLE雇員ADD FOREIGN KEY CONSTRAINT dept_id_fk ON(部門(mén)標(biāo)識(shí))REFERENCES部門(mén)(部門(mén)標(biāo)識(shí)) D.ALTER TABLE雇員ADD FOREIGN KEY 部門(mén)(部門(mén)標(biāo)識(shí))REFERENCES(部門(mén)標(biāo)識(shí))
A.USER_CONSTRAINTS B.CONSTRAINTS_ALL C.SYS_DATA_DICT D.US_CON_SYS