题目内容:
查询借阅了两本和两本以上图书的读者姓名和单位,应使用SQL语句 ( )
A.SELECT姓名,单位FROM读者; WHERE借书证号IN;
(SELECT借书证号FROM借阅;
GROUP BY借书证号HAVING COUNT(*)>=2)
B.SELECT姓名,单位FROM读者;
WHERE借书证号EXISTS;
(SELECT借书证号FROM借阅;
GROUP BY借书证号HAVING COUNT(*)>=2)
C.SELECT姓名,单位FROM读者;
WHERE借书证号EXISTS;
(SELECT借书证号FROM借阅;
GROUP BY借书证号WHERE COUNT(*)>=2)
D.SELECT姓名,单位FROM读者;
WHERE借书证号IN;
(SELECT借书证号FROM借阅;
GROUP BY借书证号WHERE COUNT(*)>=2)
参考答案:
答案解析: