将 sql case 语句嵌入到使用 FOR XML 的 sql 查询中

Question

昨天我从一位 SO 用户那里得到了一些很好的帮助（参见），这使我在实现目标方面取得了很大进展。现在，我正在尝试确定所建议的神奇添加是否可以嵌入到生成 xml 输出的现有查询中。

现有查询如下：

PROCEDURE [dbo].[CreateLandingPurchaseOrderDetails]

-- Add the parameters for the stored procedure here


@startDate DATE,
@endDate DATE


AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for procedure here
    SELECT (SELECT
            Contacts.ContactId AS '@ContactId',
            VesselOwner AS '@Owner',
            FORMAT(SUM(LandingDetails.Quantity * LandingDetails.UnitPrice), 'N2') AS '@Owed',
            SocietyMemberships.WeeklyDeductionRate AS '@WeeklyDeductionRate',
            SocietyMemberships.FromMinimumReturn AS '@FromMinimumReturn',
            Deductions.DeductionRate AS '@DeductionRate',


            (SELECT DISTINCT
                ld1.ProductId AS '@ProductId',
                FORMAT(AVG(ld1.UnitPrice), 'N2') AS '@Cost',
                FORMAT(SUM(ld1.Quantity), 'N2') AS '@Quantity'


            FROM LandingDetails ld1
            INNER JOIN dbo.LandingHeaders lh1
                ON ld1.LandingId = lh1.LandingId
            WHERE Posted = 0
            AND lh1.VesselOwner = LandingHeaders.VesselOwner
            GROUP BY ld1.ProductId
            FOR XML PATH ('Products'), TYPE)

        FROM dbo.LandingDetails
        INNER JOIN dbo.LandingHeaders
            ON LandingDetails.LandingId = LandingHeaders.LandingId
        INNER JOIN dbo.Vessels
            ON LandingHeaders.VesselId = Vessels.VesselId
        INNER JOIN dbo.Contacts
            ON Vessels.OwnerId = Contacts.ContactId
        INNER JOIN dbo.SocietyMemberships
            ON Contacts.SocietyId = SocietyMemberships.SocietyId
        INNER JOIN dbo.Deductions
            ON Vessels.DeductionId = Deductions.DeductionId
        WHERE LandingHeaders.Posted = 0
        AND LandingDate1 BETWEEN @startDate AND @endDate
        GROUP BY    ContactId,
                    VesselOwner,
                    SocietyMemberships.WeeklyDeductionRate,
                    SocietyMemberships.FromMinimumReturn,
                    Deductions.DeductionRate
        ORDER BY ContactId

        FOR XML PATH ('Owner'), TYPE)

    FOR XML PATH ('PurchaseOrders'), TYPE

END

这会产生 xml 输出；

<PurchaseOrders>
  <Owner ContactId="39" Owner="Paul Joy" Owed="1,609.39" WeeklyDeductionRate="10.00" FromMinimumReturn="110.00" DeductionRate="0.0150">
    <Products ProductId="33" Cost="5.00" Quantity="0.40" />
    <Products ProductId="34" Cost="1.80" Quantity="0.90" />
    <Products ProductId="41" Cost="2.30" Quantity="1.30" />

我想向 Owner 元素 ( TotalDeductions ) 添加一个属性。从我问的上一个问题中，我可以看出 sql 如何计算我所需要的信息以生成总扣除额字段。然而，事实证明，将该逻辑添加到 FOR XML 查询中是难以实现的。我不愿意说这是不可能的，因为在 SQL 中似乎几乎没有什么是不能用一点横向思考来完成的。

如果我只是将查询的大小写部分剪切并粘贴到我的 FOR XML 查询中，编译器会指出 Owed 不是有效名称。我明白了。但是，如果我简单地以以下方式嵌入 for xml 的所有者部分；

WITH cte AS (
 'embed the part of the FOR XML producing the owner element here
)

SELECT 
    ContactId,
    Owed,
    WeeklyDeductionRate,
    FromMinimumReturn,
    DeductionRate,
    CASE 
       WHEN Owed - (Owed * DeductionRate + WeeklyDeductionRate) > FromMinimumReturn 
       THEN Owed * DeductionRate + WeeklyDeductionRate
       ELSE Owed * DeductionRate END
    AS TotalDeductions
FROM cte

然后暂时不考虑编译错误，我不会生成我想要的 xml。

我终于找到了在 SQL 中实际上无法完成的事情，还是我只是错过了我应该拥有的显而易见的 'lateral thought'？

谢谢

Answer 1

我认为在正确的位置插入原始的 case 表达式应该可行。试试这个：

PROCEDURE [dbo].[CreateLandingPurchaseOrderDetails]

-- Add the parameters for the stored procedure here
@startDate DATE, @endDate DATE

AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for procedure here
    SELECT (
       SELECT
            Contacts.ContactId AS '@ContactId',
            LandingHeaders.VesselOwner AS '@Owner',
            FORMAT(SUM(LandingDetails.Quantity * LandingDetails.UnitPrice), 'N2') AS '@Owed',
            SocietyMemberships.WeeklyDeductionRate AS '@WeeklyDeductionRate',
            SocietyMemberships.FromMinimumReturn AS '@FromMinimumReturn',
            Deductions.DeductionRate AS '@DeductionRate',

          CASE 
             WHEN SUM(LandingDetails.Quantity * LandingDetails.UnitPrice) - (SUM(LandingDetails.Quantity * LandingDetails.UnitPrice) * DeductionRate + WeeklyDeductionRate) > FromMinimumReturn 
             THEN SUM(LandingDetails.Quantity * LandingDetails.UnitPrice) * DeductionRate + WeeklyDeductionRate
             ELSE SUM(LandingDetails.Quantity * LandingDetails.UnitPrice) * DeductionRate 
          END AS '@TotalDeductions',

            (SELECT DISTINCT
                ld1.ProductId AS '@ProductId',
                FORMAT(AVG(ld1.UnitPrice), 'N2') AS '@Cost',
                FORMAT(SUM(ld1.Quantity), 'N2') AS '@Quantity'

            FROM LandingDetails ld1
            INNER JOIN dbo.LandingHeaders lh1
                ON ld1.LandingId = lh1.LandingId
            WHERE Posted = 0
            AND lh1.VesselOwner = LandingHeaders.VesselOwner
            GROUP BY ld1.ProductId
            FOR XML PATH ('Products'), TYPE)

        FROM dbo.LandingDetails
        INNER JOIN dbo.LandingHeaders
            ON LandingDetails.LandingId = LandingHeaders.LandingId
        INNER JOIN dbo.Vessels
            ON LandingHeaders.VesselId = Vessels.VesselId
        INNER JOIN dbo.Contacts
            ON Vessels.OwnerId = Contacts.ContactId
        INNER JOIN dbo.SocietyMemberships
            ON Contacts.SocietyId = SocietyMemberships.SocietyId
        INNER JOIN dbo.Deductions
            ON Vessels.DeductionId = Deductions.DeductionId
        WHERE LandingHeaders.Posted = 0
        AND LandingDate1 BETWEEN @startDate AND @endDate
        GROUP BY    ContactId,
                    LandingHeaders.VesselOwner,
                    SocietyMemberships.WeeklyDeductionRate,
                    SocietyMemberships.FromMinimumReturn,
                    Deductions.DeductionRate
        ORDER BY ContactId

        FOR XML PATH ('Owner'), TYPE)

    FOR XML PATH ('PurchaseOrders'), TYPE

END

查询可能会得到改进，但没有 table 定义和一些样本数据，测试起来有点困难。

查看此 SQL Fiddle 以了解应该会产生相同结果的稍微调整的版本。

将 sql case 语句嵌入到使用 FOR XML 的 sql 查询中

Embedding a sql case statement into a sql query that is using FOR XML

sql

sql-server-2012

for-xml