MySQL对计算进行排序 [英] MySQL sort on a calculation

问题描述

在mySQL中是否可以对2行的计算进行排序?例如，我有2行，lp和ap，我正在尝试执行以下操作:

Is it possible to sort on a calculation of 2 rows in mySQL? For example, I have 2 rows, lp and ap I'm trying to do something like this:

SELECT * from myTbl WHERE 1 ORDER BY (lp/ap)

这不会引发错误，但是也不会根据该计算结果进行排序.有没有办法做到这一点，还是我必须将lp/ap存储在数据库中?

Which isn't throwing an error, but its also not sorting by the results of that calculation. Is there a way to do this, or do I have to store lp/ap in the database?

推荐答案

是的，这是可行的，而且确实可行.检查以下测试:

Yes, it is possible, and it does work. Check out the following test:

CREATE TABLE a(a INT, b INT);

INSERT INTO a VALUES (1, 1);
INSERT INTO a VALUES (1, 2);
INSERT INTO a VALUES (1, 3);
INSERT INTO a VALUES (1, 4);
INSERT INTO a VALUES (1, 5);
INSERT INTO a VALUES (1, 6);
INSERT INTO a VALUES (2, 1);
INSERT INTO a VALUES (2, 2);
INSERT INTO a VALUES (2, 3);
INSERT INTO a VALUES (2, 4);
INSERT INTO a VALUES (2, 5);
INSERT INTO a VALUES (2, 6);

SELECT a.a, a.b, (a/b) FROM a ORDER BY (a/b);

+------+------+--------+
| a    | b    | (a/b)  |
+------+------+--------+
|    1 |    6 | 0.1667 | 
|    1 |    5 | 0.2000 | 
|    1 |    4 | 0.2500 | 
|    2 |    6 | 0.3333 | 
|    1 |    3 | 0.3333 | 
|    2 |    5 | 0.4000 | 
|    1 |    2 | 0.5000 | 
|    2 |    4 | 0.5000 | 
|    2 |    3 | 0.6667 | 
|    2 |    2 | 1.0000 | 
|    1 |    1 | 1.0000 | 
|    2 |    1 | 2.0000 | 
+------+------+--------+

SELECT a.a, a.b FROM a ORDER BY (a/b);将返回相同的结果.

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