将 SQL 输出格式化为 JSON 的最佳方法？

编程问答 2022-04-23

问题描述

一直在尝试执行 sql 查询并输出完美的 JSON，但我遇到了问题。查询仅涉及表，当我使用“For JSON Auto”时，它会生成一个平面对象数组：enter image description here

但是存在层级关系：

Q2CNum--- 订单项---- 标识符

我尝试使用“For JSON Path”，但它只构建每个 json 对象（例如，它不会聚合其父 LineItem 下的所有标识符）。

我设法通过将表连接到自身来使它看起来像这样（相同的查询只是额外的连接，“For JSON Path Auto”似乎喜欢这个），它看起来更像这样：{{3} }

哪个好。问题是查询时间几乎是原来的 20 倍（2 秒 vs 20）。

也许我的自联接写得不好，或者联接以获得这些结果效率低下。

无论如何，如果有人知道如何做到这一点，请告诉我（不能分享太多，我相信您已经注意到图像上的颜色遮挡）。

更新：

这是查询 enter image description here 的图片。问题是我得到了一个扁平的 JSON（只是一个对象数组）。

Select OWS.Q2CNum,OWS.LineItem,OWS.Identifier,OWS.ProductType,OWS.Workstation,OWS.Calculation,OWS.UnitOfMeasure,OWS.CurrentStatus,LS.Location,LS.ProgramStamp_LocalTime
FROM table1 AS OWS
INNER JOIN table2 AS LS
ON OWS.Q2CNum = LS.[Order]
AND OWS.LineItem = LS.LineItem
AND OWS.Identifier = LS.Identifier
WHERE LS.ProgramStamp_LocalTime = 
    (Select TOP 1 LS2.ProgramStamp_LocalTime
    from dbo.view_Location_Stamps_Local AS LS2 
    Where LS2.[Order] = OWS.Q2CNum
    AND LS2.LineItem= OWS.LineItem
    AND LS2.Identifier = OWS.Identifier
    Order by LS2.ProgramStamp_LocalTime Desc) 
AND LS.[Order] = @testvar
AND LS.LineItem = COALESCE('001',OWS.LineItem)
AND LS.Identifier like '%'
---Group by Q2CNum
ORDER BY Q2CNum,LineItem,Identifier DESC
FOR JSON Auto

但我需要它是分层的：

{
    Q2CNum: value,LineItems: [{
         LineItem: value,Identifiers: [{
               identifier: value,etc...
         }],}],}

更新 2：

如果我运行这个查询，我会得到更多我想要的：

Select Q2C.Q2CNum,Li.LineItem,LS.ProgramStamp_LocalTime
FROM table1 AS OWS
INNER JOIN table2 AS Q2C
ON Q2C.Q2CNum = OWS.Q2CNum and Q2C.LineItem = OWS.LineItem and Q2C.Identifier = OWS.Identifier and Q2C.Workstation = OWS.Workstation
INNER JOIN table3 AS Li
ON Li.Q2CNum = OWS.Q2CNum and Li.LineItem = OWS.LineItem and Li.Identifier = OWS.Identifier and Li.Workstation = OWS.Workstation
INNER JOIN table4 AS LS
ON OWS.Q2CNum = LS.[Order]
AND OWS.LineItem = LS.LineItem
AND OWS.Identifier = LS.Identifier
WHERE LS.ProgramStamp_LocalTime = 
    (Select TOP 1 LS2.ProgramStamp_LocalTime
    from table5 AS LS2 
    Where LS2.[Order] = OWS.Q2CNum
    AND LS2.LineItem= OWS.LineItem
    AND LS2.Identifier = OWS.Identifier
    Order by LS2.ProgramStamp_LocalTime Desc) 
AND LS.[Order] = @testvar
AND LS.LineItem = COALESCE('001',Identifier DESC
FOR JSON Auto

但查询时间较长。

最终更新：

好的，所以 Mike Petri 的解决方案有效。我不得不修补它并试图将我的头围绕它（仍在这样做 - 在此之前我对我的 sql 技能更有信心）。无论如何，这里是我使用的最终代码（上半部分并不重要，我已经编写了该查询，唯一重要的是使用临时表。我会使用视图，但我有资源限制，所以这是更好的自动取款机）。真正的魔法开始于查询的下半部分：

IF OBJECT_ID('tempdb..#Temp') IS NOT NULL
BEGIN
    DROP TABLE #Temp;
END;

SELECT  OWS.Q2CNum,LS.ProgramStamp_LocalTime
INTO    #Temp
FROM    table1 AS OWS
        INNER JOIN table2 AS LS ON OWS.Q2CNum = LS.[Order]
                                   AND OWS.LineItem = LS.LineItem
                                   AND OWS.Identifier = LS.Identifier
WHERE   LS.ProgramStamp_LocalTime = (
                                        SELECT  TOP 1
                                                LS2.ProgramStamp_LocalTime
                                        FROM    talbe3 AS LS2
                                        WHERE   LS2.[Order] = OWS.Q2CNum
                                                AND LS2.LineItem = OWS.LineItem
                                                AND LS2.Identifier = OWS.Identifier
                                        ORDER BY
                                                LS2.ProgramStamp_LocalTime DESC
                                    )
        AND LS.[Order] = @testvar
        AND LS.LineItem = COALESCE('001',OWS.LineItem)
        AND LS.Identifier LIKE '%';

----REAL MAGIC HAPPENS HERE

SELECT t.Q2CNum,(
             SELECT disTINCT(t2.LineItem),(
                         SELECT  disTINCT(t3.Identifier),t3.Location,t3.ProgramStamp_LocalTime,(
                                    SELECT   t4.Workstation,t4.ProductType,t4.Calculation,t4.UnitOfMeasure,t4.CurrentStatus
                                    FROM #Temp AS t4
                                    WHERE t3.Q2CNum = t4.Q2CNum and t3.LineItem = t4.LineItem and  t3.Identifier = t4.Identifier
                                    FOR JSON PATH 
                                ) AS Workstations
                        FROM #Temp AS t3
                        WHERE t3.Q2CNum = t2.Q2CNum and t2.LineItem = t3.LineItem
                        FOR JSON PATH
                     ) AS Identifiers
             FROM   #Temp AS t2
             WHERE  t.Q2CNum = t2.Q2CNum
             FOR JSON PATH
         ) AS LineItems
FROM    (
            SELECT  disTINCT
                    Q2CNum
            FROM    #Temp
        ) AS t
FOR JSON AUTO;
DROP TABLE #Temp;

欢迎所有批评（我想知道的一件事是过滤（使用 Where 子句）同心 sql 选择的正确方法，即表 t4 应该只过滤到表 t3（它是直接的 Hierarchal 父级？）还是我还应该添加约束到 t4 和 t2？还是 t4 和 t？

解决方法

我使用“FOR JSON PATH”作为列表 和“对于 JSON 路径，WITHOUT_ARRAY_WRAPPER”用于项目

,

看看这是否能让你更接近。 由于您涉及连接，因此引用内部/外部查询会变得很危险。您可以将基本查询设为 VIEW，然后替换 #Temp 引用，或者使用下面的代码将其存储在临时表中，然后通过内部表引用外部表以获得您所追求的分组。> 

IF OBJECT_ID('tempdb..#Temp') IS NOT NULL
BEGIN
    DROP TABLE #Temp;
END;

SELECT  OWS.Q2CNum,OWS.LineItem,OWS.Identifier,OWS.ProductType,OWS.Workstation,OWS.Calculation,OWS.UnitOfMeasure,OWS.CurrentStatus,LS.Location,LS.ProgramStamp_LocalTime
INTO    #Temp
FROM    table1 AS OWS
        INNER JOIN table2 AS LS ON OWS.Q2CNum = LS.[Order]
                                   AND OWS.LineItem = LS.LineItem
                                   AND OWS.Identifier = LS.Identifier
WHERE   LS.ProgramStamp_LocalTime = (
                                        SELECT  TOP 1
                                                LS2.ProgramStamp_LocalTime
                                        FROM    dbo.view_Location_Stamps_Local AS LS2
                                        WHERE   LS2.[Order] = OWS.Q2CNum
                                                AND LS2.LineItem = OWS.LineItem
                                                AND LS2.Identifier = OWS.Identifier
                                        ORDER BY
                                                LS2.ProgramStamp_LocalTime DESC
                                    )
        AND LS.[Order] = @testVar
        AND LS.LineItem = COALESCE('001',OWS.LineItem)
        AND LS.Identifier LIKE '%';

SELECT  t.Q2CNum,(
             SELECT t2.LineItem,(
                         SELECT t2.Identifier AS value,t2.ProductType,t2.Workstation,t2.Calculation,t2.UnitOfMeasure,t2.CurrentStatus,t2.Location,t2.ProgramStamp_LocalTime
                         FOR JSON PATH
                     ) AS Identifiers
             FROM   #Temp AS t2
             WHERE  t.Q2CNum = t2.Q2CNum
             FOR JSON PATH,WITHOUT_ARRAY_WRAPPER
         ) AS LineItems
FROM    (
            SELECT  DISTINCT
                    Q2CNum
            FROM    #Temp
        ) AS t
FOR JSON AUTO;

DROP TABLE #Temp;
jsonsqlsqlsql-server-2017