mysql - 更新查询不起作用 - mysql

Question

以下是我的表结构:

+------+----------+
| product   | seq |
+------+----------+
|    a      | 1   |
|    b      | 1   |
|    a      | 2   |
|    a      | 3   |
|    b      | 2   |
+------+----------+

如果我的输入是 a 和 2 那么，我需要更改序列号，输出将是

+------+----------+
| product   | seq |
+------+----------+
|    a      | 2   |
|    b      | 1   |
|    a      | 1   |
|    a      | 3   |
|    b      | 2   |
+------+----------+

我使用的逻辑为:

update mytable SET seq=if(seq=2,1,2), seq=if(seq=1,2,1) where product='a'

但它不会对表进行任何更改

Answer 1

尝试这样

UPDATE table1 s1 , table1 s2 SET s1.seq=s2.seq, 
s2.seq=s1.seq WHERE s1.seq=2 and s2.seq=1 and
s1.product='a' and s2.product='a';