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20200326 连接子查询作业

本贴最后更新于 1618 天前，其中的信息可能已经时移俗易

根据老师讲的，自己整理思路（除了老师提供的，也可以是你真实遇到的面试题），将问题或答案提交到柠檬班论坛
image.png

-- 创建成绩表

   drop table if EXISTS tb_lemon_score;

   create table tb_lemon_score(
sname varchar(20),
course varchar(20),
score tinyint

);

   INSERT tb_lemon_score VALUES

('张三','语文',71),
('张三','数学',75),
('李四','语文',76),
('李四','数学',90),
('王五','语文',81),
('王五','数学',100),
('王五','英语',90);

回复形式：

1、问题+答案 或者 问题求助

2、本次系列课的心得体会，收获、建议以及评价都可以哦~~

注意：老师会评选出优秀回复+作业全勤+到课全勤，将会有大奖等着优秀的你

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  • 3ice •

    image.png

  • 其他回帖
  • zhanghang •

    老师讲的第四种答案
    select * from tb_lemon_score t1 where not exist (select * from tb_lemon_score t2 where t1.sname=t2.sname and t2.score <=80)
    可以改成 select * from tb_lemon_score t1 where t1.sname not exist (select * from tb_lemon_score t2 where t2.score <=80) 吗？课堂上发不出去。。

  • ke2beck • 
    #用一条sql语句查询每门课成绩都大于80分的学生
-- 分组查询
SELECT sname,MIN(score) 最小成绩 FROM tb_lemon_score 
	GROUP BY sname HAVING MIN(score > 80);
-- 非关联子查询
SELECT * FROM tb_lemon_score WHERE sname NOT IN 
	(SELECT sname FROM tb_lemon_score WHERE score <= 80);
-- 关联子查询
SELECT * FROM tb_lemon_score t1 WHERE NOT EXISTS 
	(SELECT * FROM tb_lemon_score t2 WHERE t1.sname=t2.sname and t2.score<=80);


#用sql语句查询所有购入商品为两种或两种以上的购物人
-- 非关联子查询
SELECT sname FROM (SELECT sname,COUNT(merch) FROM shopping_list GROUP BY sname HAVING COUNT(merch)>=2) as list;
-- 关联子查询
SELECT DISTINCT sname FROM shopping_list s1 WHERE EXISTS 
	(SELECT * FROM shopping_list s2 WHERE s2.sname=s1.sname GROUP BY s2.sname HAVING COUNT(s2.merch)>=2)
  • hljmingxi •

    image.png

    image.png

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