mysql - 在 LEFT JOIN 查询中使用 UNION 时遇到问题

Question

我有以下连接查询:

SELECT t1.*, t2.*
FROM TabContent t1
LEFT JOIN HighScore t2
  ON t1.Name = t2.Layout
WHERE TabID IN (1,2,3)
ORDER BY TabID, LayoutName

结果:

+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
|TabConID|  Name  | Tiles  | Layers | TabID  |Score ID|  fbID  | Layout |  Score |  Time  |  Stars |  Date  |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
| 1      | beetle |   30   |    5   |   1    |   1    |  2222  | beetle |  293   |  13:00 |   1    |  date  |
| 2      |elephant|   31   |    4   |   1    |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |
| 3      | dragon |   31   |    5   |   2    |   2    |  3333  | dragon |  232   |  08:35 |   2    |  date  |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+

现在我想显示 fbID 2222 拥有的所有名称(以及随之而来的数据)。我是这样做的:

SELECT t1.*, t2.* FROM TabContent t1 LEFT JOIN HighScore t2 ON t1.Name = t2.Layout WHERE fbID = 2222 AND TabID IN (1,2,3) ORDER BY TabID, LayoutName

结果:

+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
|TabConID|  Name  | Tiles  | Layers | TabID  |Score ID|  fbID  | Layout |  Score |  Time  |  Stars |  Date  |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
| 1      | beetle |   30   |    5   |   1    |   1    |  2222  | beetle |  293   |  13:00 |   1    |  date  |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+

到目前为止一切顺利!问题是，有更多的名字(大象、龙)。我也想显示这些，但将数据(接受 TabConID、名称、图 block 、图层、TabID)留空。

这是我需要的结果:

+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
|TabConID|  Name  | Tiles  | Layers | TabID  |Score ID|  fbID  | Layout |  Score |  Time  |  Stars |  Date  |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
| 1      | beetle |   30   |    5   |   1    |   1    |  2222  | beetle |  293   |  13:00 |   1    |  date  |
| 2      |elephant|   31   |    4   |   1    |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |
| 3      | dragon |   31   |    5   |   2    |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |  NULL  |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+

最好的方法是使用 UNION。如果这是一个普通的查询而不是连接的查询，则查询将如下所示(这是一个非连接示例，我没有使用它，而是为了解释一些事情):

SELECT * FROM `table` WHERE fdID = 2222 AND TabID IN (1,2,3) ORDER BY TabID, LayoutName
UNION 
select TabConID, Name, Tiles, Layers, TabID, NULL, NULL, NULL, NULL, NULL, NULL, NULL FROM `table` where fbID != 2222

不幸的是，这是一个连接查询，我不知道如何使 UNION 部分与此配合使用。也使用 Google 进行了搜索，但没有成功。

希望有人能帮忙!

Answer 1

您不需要执行 UNION 查询。只需将“fbId”条件从 WHERE 移至 JOIN 条件即可。

下面的查询应该会为您提供所需的结果:

SELECT t1.*, t2.*
FROM TabContent t1
LEFT JOIN HighScore t2
  ON t1.Name = t2.Layout AND t2.fbId = 2222
WHERE TabID IN (1,2,3)
ORDER BY TabID, LayoutName

希望对你有帮助!