MySQL使用INNER JOIN和CASE WHEN在INNER JOIN中進行選擇

Question

我有一個字符數據庫。 由於不僅要使用字符名稱，還必須將名稱與字符分開。 由於存在Male和Female角色，因此將它們保留在不同的表中：

tbl_player，tbl_maleName，tbl_femaleName

在我的MySQL Select查詢中，我想根據其性別選擇帶有INNER JOIN的正確表。 所以是這樣的：（SQL查詢是錯誤的，不起作用:(）

 SELECT tbl_player.id, 
(CASE tbl_player.gender
    WHEN 'm' THEN tbl_maleName.name
    WHEN 'f' THEN tbl_femaleName.name
END) as gamerName
, tbl_player.gender
FROM tbl_player
INNER JOIN
(CASE tbl_player.gender
    WHEN 'm' THEN tbl_maleName ON tbl_player.gamerName = tbl_maleName.id
    WHEN 'f' THEN tbl_femaleName ON tbl_player.gamerName = tbl_femaleName.id
 END)

提前致謝！

Answer 1

為什么您選擇使用2個表作為我不確定的名稱，但我不建議這樣做。

但是，請嘗試以下操作：

SELECT
      tbl_player.id
    , (CASE tbl_player.gender WHEN 'm' THEN tbl_maleName.name WHEN 'f' THEN tbl_femaleName.name END) AS gamerName
    , tbl_player.gender
FROM tbl_player
      LEFT JOIN tbl_maleName ON tbl_player.gamerName = tbl_maleName.id
                  AND tbl_player.gender = 'm'
      LEFT JOIN tbl_femaleName ON tbl_player.gamerName = tbl_femaleName.id
                  AND tbl_player.gender = 'f'

Answer 2

您需要使用Union並創建一個值為tableOption的默認值：

SELECT tbl_player.id FROM tbl_player LEFT JOIN 
(
(SELECT 'male' as tableOption, name FROM tbl_maleName)
UNION
(SELECT 'female' as tableOption, name FROM tbl_femaleName)
) as gamerName 

ON gamerName.this = tbl_player.that
WHERE gamerName.tableOption = 'female' 

如果值為女性，則將選擇第二個表的值。