35.Which two statements are true regarding constraints? (Choose two.)

35.Which two statements are true regarding constraints? (Choose two.)

A.A table can have only one primary key and one foreign key.

B.A table can have only one primary key but multiple foreign keys.

C.Only the primary key can be defined at the column and table levels.

D.The foreign key and parent table primary key must have the same name.

E.Both primary key and foreign key constraints can be defined at both column and table levels.

答案：BE

解析：

A:错误，一张表只能有一个主键，但是可以有多个外键

B:正确

C:错误，只有not null 能定义在列级别，其他约束列和表级别都可以定义

D:错误，外键和所对应的父表的列的名称不需要相同

E:正确