mysql 经典业绩查询语句面试题

一个很经典的mysql的查询语句面试题

t1

t2：

问：请写出SQL语句得到两个月的业绩，期望得到以下结果，请问SQL语句如何写？？

结果图：

 

 

 

SQL：select c.dname, a.yj '一月份',b.yj '二月份' from t1 a INNER JOIN t1 b on a.dep = b.dep INNER JOIN t2 c on a.dep = c.dep where a.mon='一月份' and b.mon='二月份' 

 

 

题2：

SELECT
	a.`year` as `year`,
	a.amount AS m1,
	b.amount AS m2,
	c.amount AS m3,
	d.amount AS m4
	
FROM
	`year` AS a
INNER JOIN `year` b ON b.year = a.year
INNER JOIN `year` AS c ON c. year = a. year
INNER JOIN `year` d ON d. year = a. year
WHERE
	a.`month` = 1
AND b.`month` = 2
AND c.`month` = 3
AND d.`month` = 4

3. 根据下面数据库，写出 挂科两门以及两门以上的学员平均分。

4.  ID  主键    CAT_id 栏目ID  good_name 商品名 

把每个栏目下ID最大的商品取出来？

    

select * from ( select * from good order by cat_id,id desc) as tmp GROUP by cat_id;