重命名UNION的JSON列

编程问答 2022-06-11

问题描述

备注：我的示例过于简化。实际上，我正在处理一个巨大的查询。但是为了说明问题/错误，让我们求助于苹果和橙子。

我的原始查询如下：

SELECT 'FruitsCount' AS "Type",(SELECT count(id) as Counter,[Name] FROM Fruits group by name FOR JSON PATH) AS "Value"

这将导致类似的结果。我们将此称为 A格式 

|---------------------|------------------------------------------------------------------------------|
|        Type         |                                   Value                                      |
|---------------------|------------------------------------------------------------------------------|
|     FruitCount      |         [{"Counter":2,"Name":"Apple"},{"Counter":3,"Name":"Orange"}]       |
|---------------------|------------------------------------------------------------------------------|

但是，现在我想创建一个水果和蔬菜计数的联合。我的查询现在看起来像这样

(SELECT count(id) as Counter,[Name] FROM Fruits group by name
UNION
SELECT count(id) as Counter,[Name] FROM vegetables group by name)
FOR JSON PATH

|---------------------|------------------------------------------------------------------------------|
|                           JSON_F52E2B61-18A1-11d1-B105-00805F49916B                                |
|---------------------|------------------------------------------------------------------------------|
|     [{"Counter":2,"Name":"Orange"},{"Counter":7,"Name":"Tomato"}]  |
|---------------------|------------------------------------------------------------------------------|

但是，我希望它采用以前的格式，其中有一个Type和Value列（格式A）。

我尝试执行以下操作：

SELECT 'FruitsCount' AS "Type",((SELECT count(id) as Counter,[Name] FROM vegetables group by name) FOR JSON PATH) as "Value"

但是，我看到Error 156: Incorrect Syntax near the keyword 'FOR'.

然后我尝试了以下操作：

SELECT 'FruitsAndVegCount' AS "Type",[Name] FROM vegetables group by name FOR JSON PATH) as "Value"

但是，我看到Error 1086: The FOR XML and FOR JSON clauses are invalid in views,inline functions,derived tables,and subqueries when they contain a set operator.

我一直想让“联盟化”查询采用格式A。

更新1：这是所需的输出

|---------------------|------------------------------------------------------------------------------------------------|
|        Type         |                                   Value                                                        |
|---------------------|------------------------------------------------------------------------------------------------|
|  FruitAndVegCount   | [{"Counter":2,"Name":"Tomato"}]  |
|---------------------|------------------------------------------------------------------------------------------------|

目标是仅包含两行（类型，值），其中一行是我指定的值（即FruitAndVegCount），而值是由联合查询创建的ResultSet的JSON。

解决方法

如果我正确理解了这个问题，则可以选择以下语句：

SELECT 
   [Type] = 'FruitAndVegCount',[Value] = (
      SELECT Counter,Name
      FROM (
         SELECT count(id) as Counter,[Name] FROM Fruits group by name
         UNION ALL
         SELECT count(id) as Counter,[Name] FROM Vegetables group by name
      ) t
      FOR JSON PATH
   )
,

您可以使用两列（类型和值）来完成此操作，如下所示。像这样

select 'FruitAndVegCount' as [Type],(select [Counter],[Name] 
         from (select count(id) as Counter,[Name] from #Fruits group by [name] 
               union all
               select count(id) as Counter,[Name] from #Vegetables group by [name]) u
          for json path) [Value];

输出

Type                Value
FruitAndVegCount    [{"Counter":2,"Name":"apple"},{"Counter":1,"Name":"pear"},{"Counter":2,"Name":"carrot"},"Name":"kale"},"Name":"lettuce"}]
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