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问工作Access SQL查询的T-SQL迁移以及编写IIF用例替换的问题
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Stack Overflow用户

提问于 2011-02-11 19:03:13

回答 3查看 330关注 0票数 2

我有两个表BMReports_FPN_Curves和BMReports_BOA_Curves，分别由名称、日期时间、句点和值组成，例如：

BM_UNIT_NAME   RunDate               Period  FPN (or BOA)
T_DRAXX-1      2010-12-01 00:03:00   1       497

RunDate字段的增量为1分钟(这是每天约1440条记录)，周期为1-48。在BMReports_FPN_Curves中，每个时间段都有完整的数据集，BMReports_BOA_Curves包含将替换这些基本值的值。

通常有重复的BOA值，Access SQL语句中的嵌套IIF语句包含一条规则，用于在任何时间点从FPN、最大BOA值或Min值中选择一个。该规则规定：

1)如果没有BOA值，请使用FPN值

2)如果有BOA值且小于FPN值，则查找并使用Min BOA值

3)如果BOA值大于FPN，则查找并使用最大BOA值

Access SQL查询运行良好，如下所示：

SELECT 
dbo_BMReports_FPN_Curves.BM_Unit_Name, 
dbo_BMReports_FPN_Curves.RunDate, 
dbo_BMReports_FPN_Curves.Period, 
dbo_BMReports_FPN_Curves.PN_Level, 

IIf(IIf(Min([dbo_BMReports_BOA_Curves]![PN_Level]) <[dbo_BMReports_FPN_Curves]![PN_Level],Min([dbo_BMReports_BOA_Curves]! [PN_Level]),Max([dbo_BMReports_BOA_Curves]![PN_Level])) Is Null, [dbo_BMReports_FPN_Curves]![PN_Level],
IIf(Min([dbo_BMReports_BOA_Curves]![PN_Level])<[dbo_BMReports_FPN_Curves]! [PN_Level],Min([dbo_BMReports_BOA_Curves]! [PN_Level]),Max([dbo_BMReports_BOA_Curves]![PN_Level]))) AS BOA

FROM dbo_BMReports_FPN_Curves LEFT JOIN dbo_BMReports_BOA_Curves ON  (dbo_BMReports_FPN_Curves.RunDate = dbo_BMReports_BOA_Curves.RunDate) AND  (dbo_BMReports_FPN_Curves.BM_Unit_Name = dbo_BMReports_BOA_Curves.BM_Unit_Name)

GROUP BY dbo_BMReports_FPN_Curves.BM_Unit_Name, dbo_BMReports_FPN_Curves.RunDate, dbo_BMReports_FPN_Curves.Period, dbo_BMReports_FPN_Curves.PN_Level

HAVING (((dbo_BMReports_FPN_Curves.BM_Unit_Name)='T_DRAXX-1'));

我用T重写了大部分查询(查询相同的Server数据源)，并让左联接、按组和让元素全部工作，但在替换IFF时，我会陷入困境，如果有些人有空的话，我会很感激您的帮助。

当前的SQL查询如下：

SELECT 
BMReports_FPN_Curves.BM_Unit_Name, 
BMReports_FPN_Curves.RunDate, 
BMReports_FPN_Curves.Period,
AVG(BMReports_FPN_Curves.PN_Level) AS FPN,

    CASE
      WHEN BMReports_BOA_Curves.PN_Level IS NULL THEN AVG(BMReports_FPN_Curves.PN_Level)
      WHEN MIN(BMReports_BOA_Curves.PN_Level) IS <  AVG(BMReports_FPN_Curves.PN_Level) THEN MIN(BMReports_BOA_Curves.PN_Level)
      ELSE MAX(BMReports_BOA_Curves.PN_Level)
    END AS BOA

FROM BMReports_FPN_Curves 
  LEFT JOIN BMReports_BOA_Curves ON BMReports_FPN_Curves.BM_Unit_Name = BMReports_BOA_Curves.BM_Unit_Name
  AND  BMReports_FPN_Curves.RunDate = BMReports_BOA_Curves.RunDate

GROUP BY BMReports_FPN_Curves.BM_Unit_Name, BMReports_FPN_Curves.RunDate, BMReports_FPN_Curves.Period
HAVING BMReports_FPN_Curves.BM_Unit_Name = 'T_DRAXX-1'
ORDER BY BMReports_FPN_Curves.BM_Unit_Name, BMReports_FPN_Curves.RunDate, BMReports_FPN_Curves.Period

case

iif

sql

tsql

ms-access

回答 3

Stack Overflow用户

回答已采纳

发布于 2011-02-11 19:36:14

SELECT  fc.BM_Unit_Name
        , fc.RunDate
        , fc.Period
        , CASE 
          WHEN AVG(bc.PN_Level) IS NULL THEN AVG(fc.PN_Level)             -- No BOA Value, use the FPN Value
          WHEN MIN(bc.PN_Level) < AVG(fc.PN_Level) THEN MIN(bc.PN_Level) -- BOA Value is less than the FPN, use the BOA Value
          ELSE MAX(bc.PN_Level)                                          -- BOA Value is greater than the FPN, use the BOA Value
          END 
FROM    dbo.BMReports_FPN_Curves fc
        LEFT JOIN dbo.BMReports_BOA_Curves bc ON fc.RunDate = bc.RunDate        
                                                 AND fc.BM_Unit_Name = bc.BM_Unit_Name
WHERE   fc.BM_Unit_Name ='T_DRAXX-1'
GROUP BY
        fc.BM_Unit_Name
        , fc.RunDate
        , fc.Period

票数 2

Stack Overflow用户

发布于 2011-02-11 19:34:18

您可能最好使用CTE来完成所有的聚合计算，然后对其执行case语句。

WITH cte 
     AS (SELECT bmreports_fpn_curves.bm_unit_name, 
                bmreports_fpn_curves.rundate, 
                bmreports_fpn_curves.period, 
                AVG(bmreports_fpn_curves.pn_level) AS fpn, 
                AVG(bmreports_fpn_curves.pn_level) AS boa, 
                MIN(bmreports_boa_curves.pn_level) minboa, 
                MAX(bmreports_fpn_curves.pn_level) maxfpn 
         FROM   bmreports_fpn_curves 
                LEFT JOIN bmreports_boa_curves 
                  ON bmreports_fpn_curves.bm_unit_name = 
                     bmreports_boa_curves.bm_unit_name 
                     AND bmreports_fpn_curves.rundate = 
                         bmreports_boa_curves.rundate 
         GROUP  BY bmreports_fpn_curves.bm_unit_name, 
                   bmreports_fpn_curves.rundate, 
                   bmreports_fpn_curves.period 
         HAVING bmreports_fpn_curves.bm_unit_name = 'T_DRAXX-1') 
SELECT bm_unit_name, 
       rundate, 
       period ,
       CASE 
              WHEN BOA IS NULL THEN FPN 
              WHEN BOA < FPN THEN MinBoa
              WEHN BOA > FPN THEN MaxBoa
              ELSE -- BOA = FPN THEN WHAT?
       END as BOA
FROM   cte

对于不支持CTE的DB，也可以在from (内联视图)中使用select。顺便说一句，Access支持这一点。

SELECT bm_unit_name, 
       rundate, 
       period ,
       CASE 
              WHEN BOA IS NULL THEN FPN 
              WHEN BOA < FPN THEN MinBoa
              WEHN BOA > FPN THEN MaxBoa
              ELSE -- BOA = FPN THEN WHAT?
       END as BOA
  FROM (
       SELECT bmreports_fpn_curves.bm_unit_name, 
                bmreports_fpn_curves.rundate, 
                bmreports_fpn_curves.period, 
                AVG(bmreports_fpn_curves.pn_level) AS fpn, 
                AVG(bmreports_fpn_curves.pn_level) AS boa, 
                MIN(bmreports_boa_curves.pn_level) minboa, 
                MAX(bmreports_fpn_curves.pn_level) maxfpn 
         FROM   bmreports_fpn_curves 
                LEFT JOIN bmreports_boa_curves 
                  ON bmreports_fpn_curves.bm_unit_name = 
                     bmreports_boa_curves.bm_unit_name 
                     AND bmreports_fpn_curves.rundate = 
                         bmreports_boa_curves.rundate 
         GROUP  BY bmreports_fpn_curves.bm_unit_name, 
                   bmreports_fpn_curves.rundate, 
                   bmreports_fpn_curves.period 
         HAVING bmreports_fpn_curves.bm_unit_name = 'T_DRAXX-1')   ) t

票数 1

Stack Overflow用户

发布于 2011-02-11 19:28:22

你试过把IIF翻译成更直译吗？例如，您的IIF链如下所示：

IIf
(
    IIf
    (
        Min([dbo_BMReports_BOA_Curves]![PN_Level]) < [dbo_BMReports_FPN_Curves]![PN_Level], 
        Min([dbo_BMReports_BOA_Curves]![PN_Level]),
        Max([dbo_BMReports_BOA_Curves]![PN_Level])
    ) Is Null,
    [dbo_BMReports_FPN_Curves]![PN_Level],
    IIf
    (
        Min([dbo_BMReports_BOA_Curves]![PN_Level]) < [dbo_BMReports_FPN_Curves]![PN_Level],
        Min([dbo_BMReports_BOA_Curves]![PN_Level]),
        Max([dbo_BMReports_BOA_Curves]![PN_Level])
    )
) AS BOA

所以直译是这样的：

(
case
    when 
        (
        case
            when Min(BMReports_BOA_Curves.PN_Level) < BMReports_FPN_Curves.PN_Level then
                Min(BMReports_BOA_Curves.PN_Level)
            else
                Max(BMReports_BOA_Curves.PN_Level)
        end
        ) is null then
        BMReports_FPN_Curves.PN_Level
    else
        (
            case
                when Min(BMReports_BOA_Curves.PN_Level) < BMReports_FPN_Curves.PN_Level then
                    Min(BMReports_BOA_Curves.PN_Level)
                else
                    Max(BMReports_BOA_Curves.PN_Level)
            end
        )
end
) as BOA

我无法访问您的完整模式或数据，因此无法测试转换，但我相信它在语法上是正确的。

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/4972952

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