SQL 连接，使用 Pivot 聚合

Posted 2023-02-15

【中文标题】SQL 连接，使用 Pivot 聚合

【英文标题】：SQL Join, Aggregate with Pivot

【发布时间】：2021-12-11 04:02:33

【问题描述】：

我正在尝试从库存系统创建自定义报告。不幸的是，在系统 UI 中，只有一个选项可以将查询用于自定义报告。我想生成带有资产状态的资产报告，例如有故障，新 - 店内，二手。

SELECT  productType.COMPONENTTYPENAME AS "Product Type", "state"."displaystate" AS "Asset State", count("resource"."resourcename" ) AS "Asset Count" FROM Resources resource
left JOIN ComponentDefinition product ON resource.COMPONENTID=product.COMPONENTID
left JOIN ComponentType productType ON product.COMPONENTTYPEID=productType.COMPONENTTYPEID
LEFT JOIN "resourcestate" "state" ON "resource"."resourcestateid" = "state"."resourcestateid"
LEFT JOIN "resourcetype" "rtype" ON "productType"."resourcetypeid" = "rtype"."resourcetypeid"
GROUP BY  state.displaystate,productType.COMPONENTTYPENAME

通过这个查询，我得到了这种格式的数据

Product Type	Asset State	Asset Count
Workstation	In Use	30
Keyb_Mouse	In Use	30
Workstation	New - In Store	10
Keyb_Mouse	Used - In Store	20
Workstation	Used - In Store	20

我想将此资产状态按行转换为（Excel 数据透视表）之类的列以获取摘要。

我尝试更改查询以将结果更改为这种格式。

Product Type	In Use	New - In Store	Used - In Store
Workstation	30	10	20
Keyb_Mouse	30	20

SELECT  productType.COMPONENTTYPENAME AS "Product Type", "state"."displaystate" AS "Asset State", count("resource"."resourcename" ) AS "Asset Count" FROM Resources resource
left JOIN ComponentDefinition product ON resource.COMPONENTID=product.COMPONENTID
left JOIN ComponentType productType ON product.COMPONENTTYPEID=productType.COMPONENTTYPEID
LEFT JOIN "resourcestate" "state" ON "resource"."resourcestateid" = "state"."resourcestateid"
LEFT JOIN "resourcetype" "rtype" ON "productType"."resourcetypeid" = "rtype"."resourcetypeid"
GROUP BY  state.displaystate,productType.COMPONENTTYPENAME

SELECT "Asset State", "In Use", "Used - In Store", "In Store", "New - In Store", "Damaged","Faulty" FROM Resources resource
PIVOT(
sum("Asset Count") for "Asset State" in ("In Use", "Used - In Store", "In Store", "New - In Store", "Damaged", "Faulty")
)

但是这个查询没有返回任何东西。请参考任何链接或视频以了解和解决此问题。提前致谢。

【问题讨论】：

如果没有样本数据、预期输出和表模式，这是无法回答的。旁白：理想情况下，您不应该使用" 进行引用，而是使用[]

【参考方案1】：

下面的查询解决了这个问题。欢迎提出改进查询的建议。

SELECT  "Product Type", "In Use", "Used - In Store", "In Store", "New - In Store", "Damaged","Faulty" FROM (
SELECT  productType.COMPONENTTYPENAME AS "Product Type", "state"."displaystate" AS "Asset State", count("resource"."resourcename" ) AS "Asset Count" FROM Resources resource
left JOIN ComponentDefinition product ON resource.COMPONENTID=product.COMPONENTID
left JOIN ComponentType productType ON product.COMPONENTTYPEID=productType.COMPONENTTYPEID
LEFT JOIN "resourcestate" "state" ON "resource"."resourcestateid" = "state"."resourcestateid"
LEFT JOIN "resourcetype" "rtype" ON "productType"."resourcetypeid" = "rtype"."resourcetypeid"
GROUP BY  state.displaystate,productType.COMPONENTTYPENAME )d
pivot
(
  max("Asset Count")
  for "Asset State" in ("In Use", "Used - In Store", "In Store", "New - In Store", "Damaged", "Faulty")
) piv

【参考方案2】：

您必须将查询的第一部分命名为 CTE，所以它应该是：

;with Resources as (
    SELECT productType.COMPONENTTYPENAME AS [Product Type],
    [state].[displaystate] AS [Asset State],
    count([resource].[resourcename] ) AS [Asset Count]
    FROM Resources resource
        left JOIN ComponentDefinition product ON resource.COMPONENTID=product.COMPONENTID
        left JOIN ComponentType productType ON product.COMPONENTTYPEID=productType.COMPONENTTYPEID
        LEFT JOIN [resourcestate] [state] ON [resource].[resourcestateid] = [state].[resourcestateid]
        LEFT JOIN [resourcetype] [rtype] ON [productType].[resourcetypeid] = [rtype].[resourcetypeid]
    GROUP BY  state.displaystate,productType.COMPONENTTYPENAME
)
SELECT [Asset State], [In Use], [Used - In Store], [In Store], [New - In Store], [Damaged], [Faulty]
FROM Resources resource
PIVOT(
    sum([Asset Count]) for [Asset State] in ([In Use], [Used - In Store], [In Store], [New - In Store], [Damaged], [Faulty])
)