Question

我有以下加入的查询：

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  |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+

现在我要显示fbID 2222拥有的所有名称（以及随附的数据）。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）。我也希望显示这些，但保留数据（接受TabConID，名称，平铺，图层，TabID）为空白。

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Query而不是一个连接的查询，那么查询看起来就像这样（这是一个非连接的例子，我不是在使用，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，这是一个加入的查询，我不知道如何使UNION部分与此一起工作。也使用谷歌搜索但没有运气。

希望有人可以提供帮助！

Answer 1

您必须更改查询并将ORDER BY置于底部，以下内容应该起作用：

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

Answer 2

您不需要执行UNION查询。只需将“fbId”条件从WHERE移动到JOIN条件。

以下查询应该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

希望它有所帮助！

Answer 3

您不能在UNION之前拥有WHERE子句。

要做你想做的事，你可能需要将联盟的第一个“腿”挤入子查询中。

在LEFT JOIN查询中使用UNION时遇到问题

3 个答案: