如何创建一个包含 JSON 的列，该列的名称是根据另一个 table 中列的值定义的？

Question

我有一个来源 table，其数据采用 VARCHAR 格式，如下例所示。我想以 JSON 格式在另一个 table 中插入数据（结果列本身可以是 JSON 或 VARCHAR 类型）。

对于每个 Id，至少有 1 JSONName/JSONValue 对。
但是每个Id的JSONName/JSONValue对的种类和数量都不一样。
每个 ID 最多可以有 50 JSONName/JSONValue 对。
ResultJSON 列值中的对顺序无关紧要。

SourceTable:
____________________________
| Id | JSONName | JSONValue |
|____|__________|___________|
| 1  | Name     | John      |
| 2  | Name     | Henry     |
| 2  | Age      | 32        |
| 3  | Age      | 56        |
| 3  | Location | US        |
| 4  | Age      | 24        |
| 4  | Name     | Andrew    |
| 4  | Location |           |

我想要的：

Expected ResultTable:
____________________________________________________
| Id |               ResultJSON                     |
|____|______________________________________________|
| 1  | {"Name":"John"}                              |
| 2  | {"Name":"Henry","Age":"32"}                  |
| 3  | {"Age":"56", "Location":"US"}                |
| 4  | {"Age":"24","Name":"Andrew","Location":null} |

我当前查询的结果：

Wrong resultTable:
_______________________________________________________________________________________________________________________________
| Id |               ResultJSON                                                                                                |
|____|_________________________________________________________________________________________________________________________|
| 1  | [{"JSONName":"Name","JSONValue":"John"}]                                                                                |
| 2  | [{"JSONName":"Name","JSONValue":"Henry"},{"JSONName":"Age","JSONValue":"32"}]                                           |
| 3  | [{"JSONName":"Age","JSONValue":"56"},{"JSONName":"Location","JSONValue":"US"}]                                          |
| 4  | [{"JSONName":"Age","JSONValue":"24"},{"JSONName":"Name","JSONValue":"Andrew"},{"JSONName":"Location","JSONValue":null}] |

当前查询：

INSERT INTO ResultTable
(
     Id
    ,ResultJSON
)
SELECT
     SourceTable.Id
    ,JSON_AGG(SourceTable.JSONName,SourceTable.JSONValue)
FROM SourceTable
INNER JOIN OtherTable ON SourceTable.Id=OtherTable.Id

是否可以使用 Teradata JSON 函数来实现？如果不是，最优化的查询是什么？

Answer 1

这是我最后得到的查询：

INSERT INTO DB.RESULT_TABLE
(
     ResultId
    ,ResultJSON
)
WITH RECURSIVE MergedTable (Id, mergedList, rnk)
AS
(
    SELECT
         Id
        ,TRIM('"' || JSONName ||'":'|| COALESCE('"' || JSONValue || '"','null')) AS mergedList
        ,rnk
    FROM DB.SOURCE_TABLE
    WHERE rnk = 1

    UNION ALL

    SELECT
         SourceTable.Id
        ,MergedTable.mergedList || ',' || TRIM('"' || SourceTable.JSONName ||'":' || COALESCE('"' || SourceTable.JSONValue || '"','null')) AS mergedList
        ,SourceTable.rnk
    FROM DB.SOURCE_TABLE SourceTable
    INNER JOIN MergedTable MergedTable
        ON MergedTable.rnk + 1 = SourceTable.rnk
        AND  SourceTable.Id = MergedTable.Id
)
SELECT
     MergedTable.Id                       AS ResultId
    ,'{' || MergedTable.mergedList || '}' AS ResultJSON
FROM MergedTable
QUALIFY RANK() OVER (PARTITION BY ResultId ORDER BY rnk DESC) = 1
;

Answer 2

您可以使用 RegEx 删除不需要的部分：

SELECT
   SourceTable.Id
  ,RegExp_Replace(Cast(Json_Agg(SourceTable.JSONName AS "#A",SourceTable.JSONValue AS "#B") AS VARCHAR(32000)), '"#A":|,"#B"|^\[|\]$|}(?=,{")|(?<="},){')
FROM SourceTable
GROUP BY 1

RegEx 删除了以下所有内容：

"#A":
,"#B"
前导[
尾随]
} 如果后面跟着,{"
{ 如果跟随 "},

编辑：

根据评论，此 RegEx 留下了多余的左大括号。这似乎效果更好：

'"#A":|,"#B"|^[|]$|}(?=,)|(?<=,){'

如何创建一个包含 JSON 的列，该列的名称是根据另一个 table 中列的值定义的？

How to create a column containing a JSON that has names defined from the value of a column in another table?

sql

json

teradata