52语句“SELECT * FROM tb(emp ORDER BY age DESC LIMIT 1,3;”执行后返回的记录是()

A. ND关键字可以连接两个或者多个查询条件,只有满足所有条件的记录才会被返回。

A. UNION

B. DISTINCT

C. LIMIT

D. REMOVE

A. select pid from tbⱣⱤorder where count(pid)>3;

B. select pid from tbⱣⱤorder where max(pid)>3;

C. select pid from tbⱣⱤorder group by pid having count(pid)>3;

D. select pid from tbⱣⱤorder group by pid having count(pid)>=3;

A. TE语句,本质上两者没有区别。

A. CHECK是能够单独执行的SQL语句

B. 该表达式定义了对字段score的約束

C. score的取值范围为0-100 (包含0和100)

D. 更新表中数据时,检查score的值是否满足CHECK約束

A. update user set id = u001 ;

B. update user(id,username) values('u001','jack');

C. update user set id='u001',username='jack';

D. update into user set id = 'u001', username='jack';

A. 视图可以嵌套

B. 视图可以创建索引

C. 视图包含数据

D. 视图不能与表一起使用

A. ND 值2代表一个范围时,值1表示起始值,值2表示结束值,值1与值2都是包含边界的。

A. SELECT COUNT(*) FROM score GROUP BY sno;

B. SELECT COUNT(*) FROM score GROUP BY cname;

C. SELECT SUM(*) FROM score GROUP BY cname;

D. SELECT SUM(*) FROM score GROUP BY sno;