特定的合并sql中的2列(不包括其中一列) [英] Specific merge 2 columns in sql excluding one of them

问题描述

我有这样的桌子:

| user1 | user2 |
|   1   |   2   |
|   3   |   1   |
|   4   |   1   |
|   1   |   5   |
|  ...  |  ...  |

我想将此列合并为一，但在新合并的列中必须为数字，这与给定的数字不相等.那就是如果我在上表中使用此查询并给出数字1:

I wanna merge this columns into one, but in new merged column must be number, which not equals with one given. That is if I used this query on table above and give number 1:

SELECT CONCAT(user1, user2) AS user FROM table WHERE user1 = 1 or user2 = 1

我已经退回了这个

| user |
|  12  |
|  31  |
|  41  |
|  15  |
|  ..  |

何时应返回此值:

| user  |
|   2   |
|   3   |
|   4   |
|   5   |
|  ...  |

1是一个示例.该怎么做?

1 is an example. How to do that ?

推荐答案

SELECT IF(user1 = 1, user2, user1) AS user
FROM table
WHERE user1 = 1 OR user2 = 1

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