假定USER表的PRIMARY KEY约束名为USER_ID_PK,下面哪一个语句将删除这个约束( )
DROP CONSTRAINT USER_ID_PK;
ALTER TABLE USER DROP USER_ID_PK;
ALTER TABLE USER DROP CONSTRAINT USER_ID_PK;
ALTER TABLE USER DROP PRIMARY KEY;
青云测评
青云测评
假定USER表的PRIMARY KEY约束名为USER_ID_PK,下面哪一个语句将删除这个约束( )
DROP CONSTRAINT USER_ID_PK;
ALTER TABLE USER DROP USER_ID_PK;
ALTER TABLE USER DROP CONSTRAINT USER_ID_PK;
ALTER TABLE USER DROP PRIMARY KEY;
