T-SQL Working Access SQL查询的迁移具有关于IIF的替换的问题

Question

我有两个表 bmreports_fpn_curves 和 bmreports_boa_curves ，每个名称，日期时间，周期和值组成：

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

.

与rundate字段递增一分钟（每天C.1440记录），并且期间为1-48。在 bmreports_fpn_curves 中，我对每个时间段都有一个完整的数据集， bmreports_boa_curves 包含将替换这些基本值的值。

通常有重复的蟒蛇值和接入中的嵌套的IIF语句 sql语句包含一个规则，以便为任何时间点选择FPN，最大BOA值或MIN BOA值的规则。规则规定：

1）如果没有BOA值，请使用FPN值
2）如果存在蟒蛇值，它少于FPN，查找和使用MIN BOA值
3）如果存在蟒蛇值，它大于FPN，请找到并使用Max Boa值

访问SQL查询工作完美，如下：

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'));

.

我已经重新编写了T-SQL中的大部分查询（查询相同的SQL Server数据源），并具有左连接，组和具有元素的所有工作，但我在替换时陷入困境对于iff而且如果有些人有几个备用速度，那就真的很欣赏。

SQL查询当前代表：

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

.

Answer 1

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

.

Answer 2

您可能更好地使用CTE来完成所有聚合计算，然后从中执行案例语句

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DB，不支持CTES，您还可以在FROM中使用SELECT（内联视图）。顺便访问支持此问题。

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

.

Answer 3

你有没有尝试过一个更字面的IIF案例翻译？例如，您的IIF链看起来像这样：

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

. 所以字面翻译将是这样的：

(
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

.

我没有访问完整的架构，也不访问数据，所以我无法测试翻译，但我相信它在句子上是正确的。