如何根据重复的行列值添加列值？

Question

我使用 sql 从数据库中选择了 table 个值。

SELECT

  a.Chapter, a.price, b.book

FROM 

  Table1 a, Table2 b, Table3 c

WHERE

  a.id = c.id and b.id = c.id2

GROUP BY

  a.Chapter, a.price

ORDER BY

  a.Chapter

它带回的值是：

|Chapter|Price|book|
|_______|_____|____|
|01     | 25  |eg1 |
|01     | 23  |eg2 |
|01     | 9   |eg3 |
|02     | 15  |eg4 |
|02     | 89  |eg5 |
|02     | 11  |eg6 |
|02     | 3   |eg7 |
|02     | 25  |eg8 |

我如何获取每个重复的 01 的价格（顺便说一句，它是字符串格式，因为它不是一本书的章节）并将它们加在一起并使它们成为新价格？例如：

Chapter   Price
   01      57   
   02      143

The book part isn't really important at the moment so it can be excluded

Answer 1

你试过 DISTINCT 了吗？

SELECT DISTINCT x
from table1
where example = example2

Answer 2

SELECT a.Chapter, sum(a.price)
FROM Table1 a
INNER JOIN Table3 c on c.id = a.id
INNER JOIN Table2 b on b.id = c.id
GROUP BY
  a.Chapter
ORDER BY
  a.Chapter

Answer 3

你的做法是错误的。你按章节和价格分组，但你也 select 这本书。这本书将是任意选择的章节和价格匹配的书籍之一。所以有了这个数据

book chapter price
eg1  01      25
eg1  02      30
eg2  01      25
eg3  01      30

你可能会得到

book chapter price
eg1  01      25
eg1  02      30
eg3  01      30

从而抑制图书eg2.

无论如何，GROUP BY chapter 每章都有一个结果行。您得到 SUM.

的总和

select chapter, sum(price)
from chapters
group by chapter;
order by chapter;

Answer 4

只用一个table就可以实现

SELECT
  a.Chapter, SUM(a.price) as price
FROM 
  Table1 a
GROUP BY
  a.Chapter
ORDER BY
  a.Chapter

如何根据重复的行列值添加列值？

How do I add up values for columns based on repeating row column value?

mysql

sql

group-by

repeat