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.
Answer: BE
答案解析：
参考：http://blog.csdn.net/rlhua/article/details/12905109
A. 一个表只能有一个主键和一个外键,不正确因为一个表只能有一个主键，但可以有多个外键
B. 一个表只能有一个主键，但可以有多个外键,正确。
C. 只有主键能被定义成列级或表级，不正确因为除了NOT NULL只有被定义成列级，其它的约束都可以被定义成列级或表级
D. 外键和父表主键必须名字相同，不正确因为名字可以不同，但是数据类型需一致
E. 主键和外键都可以被定义成列级或表级