假设需要为表Customer增加主键约束,主键列为customer_id,则可以使用哪条语句?
A.
Alter table CUSTOMER ADD PK_CUSTOMER PRIMARY KEY ("CUSTOMER_ID");
B.
Alter table CUSTOMER ADD CONSTRAINT PRIMARY KEY ("CUSTOMER_ID");
C.
Alter table CUSTOMER ADD CONSTRAINT PK_CUSTOMER ("CUSTOMER_ID");
D.
lter table CUSTOMER ADD CONSTRAINT PK_CUSTOMER PRIMARY KEY ("CUSTOMER_ID")