如何清理这些Sql数据？

这是一个问题的后续问题

我在一个db表中有以下数据

Name                LeftId    RightId
------------------------------------------
Cat                     1  
Cat                     1
Dog                     2
Dog                     2
Dog                               3
Dog                               3
Gerbil                  4         5 
Cat                
Bird
Cow                     6
Cow
Cow                               7
Dog                     8         9

请注意，有些行没有LeftId和RightId的数据

现在，我想做的是找到两个不同的查询

在两列之一中至少有一个Id的所有行，以及在这两个Id列中都没有数据的行

例如

LeftId和RightId为NULL的所有行都按相同的名称分组。如果另一行（具有相同名称）的LeftId或RightId中有值，则不会返回此名称

例如

嗯

---

编辑：正确地改写了第一个问题。

如果我理解正确，那么这就相当微不足道了：

1：

2：

如果这不正确，也许你可以澄清一下

编辑：已更新（查询1）

问题2）

---

我希望我在这里理解正确

问题1：

SELECT t1.Name, COALESCE(MIN(t1.LeftID), MIN(t1.RightID))
FROM Table t1
WHERE EXISTS(SELECT t2.Name
             FROM Table t2
             WHERE t2.Name = t1.Name 
             AND   t2.LeftID IS NULL AND t2.RightID IS NULL)
AND   COALESCE(MIN(t1.LeftID), MIN(t1.RightID)) IS NOT NULL
GROUP BY t1.Name

SELECT [Name], [LeftID], [RightID]

FROM [TestTable]

WHERE -- "All rows which have at least 1 Id in one of the two columns"
      ([LeftID] IS NOT NULL OR [RightID] IS NOT NULL)
      OR
      -- "Rows with NO data in both of those two Id columns"
      ([LeftID] IS NULL AND [RightID] IS NULL)

问题2：

SELECT t1.Name
FROM Table t1
WHERE NOT EXISTS(SELECT t2.Name
                 FROM Table t2
                 WHERE t2.Name = t1.Name
                 AND   (t2.LeftID IS NOT NULL OR t2.RightID IS NOT NULL))

SELECT [Name], [LeftID], [RightID]

FROM [TestTable]

WHERE -- "All the rows where LeftId and RightId are NULL
      -- grouped by the same name"
      ([LeftID] IS NULL AND [RightID] IS NULL)
      AND
      -- "If another row (with the same name) has a value
      -- in the LeftId or RightId, this name will not be returned"    
      ([Name] NOT IN (SELECT DISTINCT [Name] FROM [TestTable]
                      WHERE [LeftID] IS NOT NULL
                            OR
                            [RightID] IS NOT NULL))

GROUP BY [Name], [LeftID], [RightID]

问题1：

SELECT t1.Name, COALESCE(MIN(t1.LeftID), MIN(t1.RightID))
FROM Table t1
WHERE EXISTS(SELECT t2.Name
             FROM Table t2
             WHERE t2.Name = t1.Name 
             AND   t2.LeftID IS NULL AND t2.RightID IS NULL)
AND   COALESCE(MIN(t1.LeftID), MIN(t1.RightID)) IS NOT NULL
GROUP BY t1.Name

SELECT [Name], [LeftID], [RightID]

FROM [TestTable]

WHERE -- "All rows which have at least 1 Id in one of the two columns"
      ([LeftID] IS NOT NULL OR [RightID] IS NOT NULL)
      OR
      -- "Rows with NO data in both of those two Id columns"
      ([LeftID] IS NULL AND [RightID] IS NULL)

问题2：

SELECT t1.Name
FROM Table t1
WHERE NOT EXISTS(SELECT t2.Name
                 FROM Table t2
                 WHERE t2.Name = t1.Name
                 AND   (t2.LeftID IS NOT NULL OR t2.RightID IS NOT NULL))

SELECT [Name], [LeftID], [RightID]

FROM [TestTable]

WHERE -- "All the rows where LeftId and RightId are NULL
      -- grouped by the same name"
      ([LeftID] IS NULL AND [RightID] IS NULL)
      AND
      -- "If another row (with the same name) has a value
      -- in the LeftId or RightId, this name will not be returned"    
      ([Name] NOT IN (SELECT DISTINCT [Name] FROM [TestTable]
                      WHERE [LeftID] IS NOT NULL
                            OR
                            [RightID] IS NOT NULL))

GROUP BY [Name], [LeftID], [RightID]

结果:

Name                                               LeftID      RightID
-------------------------------------------------- ----------- -----------
Cat                                                1           NULL
Cat                                                1           NULL
Dog                                                2           NULL
Dog                                                2           NULL
Dog                                                NULL        3
Dog                                                NULL        3
Gerbil                                             4           5
Cat                                                NULL        NULL
Bird                                               NULL        NULL
Cow                                                6           NULL
Cow                                                NULL        NULL
Cow                                                NULL        7
Dog                                                8           9

(13 row(s) affected)

Name                                               LeftID      RightID
-------------------------------------------------- ----------- -----------
Bird                                               NULL        NULL

(1 row(s) affected)

---

对于第一个查询，您需要满足以下两个条件的行：

行中的

名称

出现在表中的同一行中，

LeftId

和

righID

均为空

行中的

名称

出现在同一行的表中，其中

左ID

和

右ID

中至少有一个不为空

那么#1是通过以下方式完成的：

SELECT Name FROM Tbl WHERE (LeftId IS NULL) AND (RightId IS NULL)

SELECT Name FROM Tbl WHERE (LeftId IS NOT NULL) OR (RightId IS NOT NULL)

和#2由以下人员完成：

SELECT Name FROM Tbl WHERE (LeftId IS NULL) AND (RightId IS NULL)

SELECT Name FROM Tbl WHERE (LeftId IS NOT NULL) OR (RightId IS NOT NULL)

您可以将它们相交以查看两个列表中出现的

名称

s：

SELECT Name FROM Tbl WHERE (LeftId IS NULL) AND (RightId IS NULL)
INTERSECT
SELECT Name FROM Tbl WHERE (LeftId IS NOT NULL) OR (RightId IS NOT NULL)

返回：

Name
----
Cat
Cow

Name  Id
----  --
Cat   1
Cow   6

Name
----
Bird

但是您需要

LeftId

和

righID

，而您不关心哪个，因此我想我们将在名称上聚合：

SELECT Name, MIN(LeftId) AS LeftId, MIN(RightId) AS RightId 
    FROM Tbl WHERE Tbl.Name IN (
      SELECT Name FROM Tbl WHERE (LeftId IS NULL) AND (RightId IS NULL)
      INTERSECT
      SELECT Name FROM Tbl WHERE (LeftId IS NOT NULL) OR (RightId IS NOT NULL)
    )
GROUP BY Name

返回

Name  LeftId  RightId
----  ------  -------
Cat   1
Cow   6       7

已经建议使用COALESE将这两个ID转换为单个ID。那么这个呢：

SELECT Name, COALESCE(MIN(LeftId),MIN(RightId)) AS Id 
    FROM Tbl WHERE Tbl.Name IN (
      SELECT Name FROM Tbl WHERE (LeftId IS NULL) AND (RightId IS NULL)
      INTERSECT
      SELECT Name FROM Tbl WHERE (LeftId IS NOT NULL) OR (RightId IS NOT NULL)
    )
GROUP BY Name

返回：

Name
----
Cat
Cow

Name  Id
----  --
Cat   1
Cow   6

Name
----
Bird

---

对于第二个查询，您需要符合以下条件的行：

Name

仅在没有

LeftId

和

righID

我想不出用一组条件在SQL中实现这种自引用查询的方法，所以我将把它分解为两个条件。必须遵守这两项规定才能被接受：

Name

出现在没有

LeftId

和

righID

Name

不会出现在具有

LeftId

或

righID

的行中

做#1很简单：

SELECT Name FROM Tbl WHERE (LeftId IS NULL) AND (RightId IS NULL)

但是#2很棘手。当然，执行与#2相反的操作（“所有出现在具有

LeftId

或

righID

的行中的

Name

）与前面一样：

SELECT Name FROM Tbl WHERE (LeftId IS NOT NULL) OR (RightId IS NOT NULL)

现在是棘手的一点-我们想要所有服从#1但不服从#2相反的行。这就是除了之外的有用的地方：

SELECT Name FROM Tbl WHERE (LeftId IS NULL) AND (RightId IS NULL)
EXCEPT
SELECT Name FROM Tbl WHERE (LeftId IS NOT NULL) OR (RightId IS NOT NULL)

返回：

Name
----
Cat
Cow

Name  Id
----  --
Cat   1
Cow   6

Name
----
Bird

---

这正是我们想要的！

第二个是不正确的。对于该查询，我是在所有行（按名称分组）之后，这些行（每个组）都没有Id。因此，在您的代码中，Cow有一行具有两个空值，但它也有一些其他行，其中一个字段具有数字。因此，不应返回Cow。否：（我重新编写了两个q。也许这会有帮助/澄清。第一个查询没有在sql2008中运行。您最好给出您得到的错误。“它没有运行”给我们提供了完全没有依据的信息，我们无法帮助您。但是，我想我可以猜到您需要一个GROUP by子句，因为聚合函数MIN（）这就是您得到的错误。我编辑了答案，请重试。