SQL select 值基于其他两列

Question

如果我table喜欢：

Name	Subject	Score
Tom	Math	90
Tom	Physics	70
Jerry	Math	70
Jerry	Physics	90
Bob	Math	80
Bob	Physics	80

如何编写 SQL 代码来查找数学比物理更好的人？

输出应该是：

Name
Tom

Answer 1

我将在 table 上加入两个查询，一个用于数学，一个用于物理：

SELECT m.name
FROM   (SELECT name, score
        FROM   mytable
        WHERE  subject = 'Math') m
JOIN   (SELECT name, score
        FROM   mytable
        WHERE  subject = 'Physics') p ON m.name = p.name AND m.score > p.score

Answer 2

多种方式。一种方法是说您想知道哪些名字有数学，哪些人也有分数较低的学科物理，所以

select *
from t
where subject='maths' and exists (
  select * from t t2 where t2.name=t.name 
    and t2.subject='physics'
    and t2.score < t.score
)

Answer 3

你可以在db-fiddle中用数据查看我的解决方案。

总之，您可以申请以下查询

SELECT 
      s1.Name
      FROM TableName s1, TableName s2
WHERE s1.Name = s2.Name 
AND s1.Subject = 'Math' AND s2.Subject = 'Physics' 
AND s1.Score > s2.Score

SQL select 值基于其他两列

SQL select values based on other two columns

sql

select