TSQL Having 子句在条件下未按预期执行

Question

DECLARE @ComparisonMonth DATE
SET @ComparsionMonth '09-01-2018'

SELECT 
    Date, Sales, CustomerID 
FROM
    Database1 t1
WHERE
    Date >= CASE 
               WHEN (SELECT MAX(Date) 
                     FROM Database1 t2 
                     INNER JOIN ON t1.PlayerID = t2.PlayerID) >= DATEADD(month, -4, @ComparisonMonth) 
                    AND (SELECT MAX(Date) 
                         FROM Database1 t2 
                         INNER JOIN ON t1.PlayerID = t2.PlayerID) < DATEADD(month, -1, @ComparsionMonth) 
                  THEN DATEADD(month, -4, @ComparisonMonth)
               WHEN (SELECT MAX(Date) 
                     FROM Database1 t2 
                     INNER JOIN ON t1.PlayerID = t2.PlayerID) >= DATEADD(month, -7, @ComparisonMonth) 
                    AND (SELECT MAX(Date) 
                         FROM Database1 t2 
                         INNER JOIN ON t1.PlayerID = t2.PlayerID) < DATEADD(month, -4, @ComparsionMonth) 
                  THEN DATEADD(month, -7, @ComparisonMonth)
            END
        AND Date < CASE 
                      WHEN (Select MAX(Date) from Database1 t2 INNER JOIN on t1.PlayerID=t2.PlayerID) >= DATEADD(month, -4, @ComparisonMonth) 
                           AND (Select MAX(Date) from Database1 t2 INNER JOIN on t1.PlayerID=t2.PlayerID) < DATEADD(month, -1, @ComparsionMonth)          
                         THEN DATEADD(month, -1, @ComparisonMonth)
                      WHEN (Select MAX(Date) from Database1 t2 INNER JOIN on t1.PlayerID=t2.PlayerID) >= DATEADD(month, -7, @ComparisonMonth) 
                           AND (Select MAX(Date) from Database1 t2 INNER JOIN on t1.PlayerID=t2.PlayerID) < DATEADD(month, -4, @ComparsionMonth) 
                         THEN DATEADD(month, -4, @ComparisonMonth)
                    END

    GROUP BY
        CustomerID, Date

基本上，我只想根据客户上次购买商品的时间显示特定时期的价值。例如，如果客户在过去 3 个月内最后购买了一件商品，我想获取他们过去 3 个月的所有交易。相反，我正在为 3 个月前最后一次来的客户获取 6 个月的交易。

非常感谢您的帮助，如果您需要任何说明，请告诉我。

Answer 1

我的建议是停止尝试一次实现所有目标。将您的查询拆分为：

1 找到您需要的客户。非常简单的查询和精确的过滤条件：

DECLARE @Customers TABLE (CustomerID INT NOT NULL PRIMARY KEY, LastPurchase DATE, FirstTran DATE)

INSERT INTO @Customers(CustomerID, LastPurchase, FirstTran)
SELECT 
    CustomerID, MAX(Date), DATEADD(MM, -3, MAX(Date))
FROM Database1 d
WHERE d.date >= @ReportDate
GROUP BY CustomerID

2 获取他们的交易。现在您再次拥有良好的过滤器（连接谓词）- CustomerID。帮助服务器过滤大 table - 从收集的数据中找到绝对最小的日期。

DECLARE @MinDate DATE

SELECT @MinDate = MIN(FirstTran)
FROM @Customers

SELECT d.*
FROM Database1 d
INNER JOIN @Customers c
on c.CustomerID = d.CustomerID
WHERE d.Date >= c.FirstTran
  AND d.Date >= @MinDate

测试你的解决方案，如果你想出一些微小的单步解决方案 - 按照你的意愿重构这段代码。

TSQL Having 子句在条件下未按预期执行

TSQL Having clause not performing as expected with condition

tsql

sql-server

having