A.CHECK B.PRIMARY KEY C.FOREIGN KEY D.UNIQUE
A.主鍵可以用來確保表中不存在重復(fù)的數(shù)據(jù)行 B.一個(gè)表必須有一個(gè)主鍵 C.一個(gè)表只能有一個(gè)主鍵 D.只能對整數(shù)型列設(shè)置主鍵
A.Select * into customers from clients B.Select into customers from clients C.Insert into customers select * from clients D.Insert customers select * from clients