MySQL按计算排序

Question

是否可以在mySQL中对2行进行排序？例如,我有2个排,lp和ap我想要做这样的事情:

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

哪个不是抛出错误,但它也没有按计算结果排序.有没有办法做到这一点,还是我必须在数据库中存储lp/ap？

Answer 1

是的,它是可能的,它确实有效.看看以下测试:

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); 会返回相同的结果.

Answer 2

 SELECT *, (lp/ap) AS calculation from myTbl ORDER BY calculation

如果(lp/ap)有效,这应该可以解决问题.