mysql - 选择表中只有一个值的行

Question

这是我的表格:

(我之前没有说过，colum2是字符串类型，不是整数，抱歉)

╔══════╦═══════╗
║ USER ║ COLOR ║
╠══════╬═══════╣
║ a    ║ Red   ║
║ b    ║ Blue  ║
║ c    ║ Blue  ║
║ b    ║ Red   ║
║ a    ║ Red   ║
║ c    ║ White ║
╚══════╩═══════╝

我只需要颜色=“红色”的行。
它必须返回“a”(“b”也包含值“Blue”)。

如何设置选择？感谢和问候

Answer 1

SELECT  column1
FROM    TableName
GROUP   BY Column1
HAVING  COUNT(DISTINCT column2) = 1
        AND MAX(column2) = 1

• SQLFiddle Demo

还有另一种方法

SELECT  column1
FROM    TableName
GROUP   BY Column1
HAVING  MAX(column2) = MIN(column2) AND
        MAX(column2) = 1

• SQLFiddle Demo

更新1

SELECT  user
FROM    TableName
GROUP   BY user
HAVING  SUM(color = 'red') = COUNT(*)

• SQLFiddle Demo