MySQL根據同一列中的值更新單個列上的多個行

Question

我有一個如下所示的表：

ID     Key     Value     Order
1      gender  m         0
2      gender  f         0

34     age     10        0
35     age     80        0

要更新這些行，我必須使用以下內容：

UPDATE `DemoGroup` SET `value` = 'male' WHERE `value` = 'm'
UPDATE `DemoGroup` SET `value` = 'female' WHERE `value` = 'f'
UPDATE `DemoGroup` SET `value` = '10-19' WHERE `value` = '10'
UPDATE `DemoGroup` SET `value` = '80-89' WHERE `value` = '80'

有沒有辦法將此合並到一個更新語句中，而不使用ID（不保證是相同的），例如（即使這不起作用）...

UPDATE `DemoGroup` 
SET `value`= CASE `value`
    WHEN 'm' THEN 'male',
    WHEN 'f' THEN 'female' END 
WHERE `value` = 'm' OR `value` = 'f'

如果我能弄清楚如何為每一行設置Order字段，那么更多的獎勵（但不是nesseary）...

Answer 1

你應該更新值不僅基於值的value而且基於key的值，否則你可以在key為'shirt-size'時將'm'更新為'male'。

UPDATE `DemoGroup` 
SET `value` = CASE 
    WHEN (`key`, `value`) = ('gender', 'm') THEN 'male'
    WHEN (`key`, `value`) = ('gender', 'f') THEN 'female'
    WHEN (`key`, `value`) = ('age', '10')   THEN '10-19'
    WHEN (`key`, `value`) = ('age', '80')   THEN '80-89'
    ELSE `value` -- no-op for other values
  END 
WHERE `key` IN ('gender','age');

Answer 2

MySQL確實有一個案例功能。 嘗試：

UPDATE DemoGroup SET `value` = 
CASE `value` WHEN 'm' THEN 'male'
WHEN 'f' THEN 'female'
WHEN '10' THEN '10-19'
WHEN '80' THEN '80-89' END;