Sql server SQL Server案例语句性能不好

我有一个包含多个CASE语句的查询，如下所示。即使在适当的索引之后，也需要花费大量的时间来执行。case语句上的Sum操作导致性能不佳。如何重新编写上述查询以提高性能

SELECT H.Item,
       SUM(CASE A.CategeoryId
             WHEN 123 THEN NULLIF(IIF(C.IsActive = 0
                                      AND ( ( c.RowID IN ( 2, 4 )
                                              AND H.SubId <> ISNULL(C.ItemId, 0) )
                                             OR ( c.RowId NOT IN ( 2, 4 )
                                                  AND H.SubId = ISNULL(C.ItemId, 0) ) ), 0, A.Sales), 0)
             ELSE 0
           END) AS [TotalSales1],
       SUM(CASE A.CategeoryId
             WHEN 198 THEN NULLIF(IIF(C.IsActive = 0
                                      AND ( ( c.RowID IN ( 2, 4 )
                                              AND H.SubId <> ISNULL(C.ItemId, 0) )
                                             OR ( c.RowId NOT IN ( 2, 4 )
                                                  AND H.SubId = ISNULL(C.ItemId, 0) ) ), 0, A.Sales), 0)
             ELSE 0
           END) AS [TotalSales2],
       '',
       '',
       '',
       '',
       ''
FROM   SubItem AS H
       INNER JOIN Item AS C WITH (NOLOCK)
               ON H.Item = C.ItemId
       LEFT OUTER JOIN #temp1 AS A
                    ON H.SubId = A.ItemId
WHERE  H.Productid = 99
GROUP  BY H.Item,
          C.ItemId,
          C.RowID 

---

发布执行计划。这将不是直接的总和或情况。也许您的正确索引可以改进。也许temp1没有索引，临时表经常被忽略。与其期望我们从您的查询中解析和理解您的意图，不如用文字描述您正在尝试做什么？另外，添加示例数据和预期结果。