Question

我有这样的查询：

UPDATE RM
SET RM.WEEK_1 = (
    SELECT P.AVERAGE_AVAI FROM dbo.f_SCAVAI_GetWeekAverage(RM.OPRO_KEY, @WEEKS_MONTH, @cWorkDaysOnly, RM.KAPACITETA) P WHERE P.WEEKOFMONTH = 1
),
RM.WEEK_2 = (
    SELECT P.AVERAGE_AVAI FROM dbo.f_SCAVAI_GetWeekAverage(RM.OPRO_KEY, @WEEKS_MONTH, @cWorkDaysOnly, RM.KAPACITETA) P WHERE P.WEEKOFMONTH = 2
),
RM.WEEK_3 = (
    SELECT P.AVERAGE_AVAI FROM dbo.f_SCAVAI_GetWeekAverage(RM.OPRO_KEY, @WEEKS_MONTH, @cWorkDaysOnly, RM.KAPACITETA) P WHERE P.WEEKOFMONTH = 3
),
RM.WEEK_4 = (
    SELECT P.AVERAGE_AVAI FROM dbo.f_SCAVAI_GetWeekAverage(RM.OPRO_KEY, @WEEKS_MONTH, @cWorkDaysOnly, RM.KAPACITETA) P WHERE P.WEEKOFMONTH = 4
),
RM.WEEK_5 = (
    SELECT P.AVERAGE_AVAI FROM dbo.f_SCAVAI_GetWeekAverage(RM.OPRO_KEY, @WEEKS_MONTH, @cWorkDaysOnly, RM.KAPACITETA) P WHERE P.WEEKOFMONTH = 5
),
RM.WEEK_6 = (
    SELECT P.AVERAGE_AVAI FROM dbo.f_SCAVAI_GetWeekAverage(RM.OPRO_KEY, @WEEKS_MONTH, @cWorkDaysOnly, RM.KAPACITETA) P WHERE P.WEEKOFMONTH = 6
)
FROM @ROOMS_BY_DEPA_KEY1 RM

这样可行，但速度很慢，因为每周的号码都会调用dbo.f_SCAVAI_GetWeekAverage。此函数返回给定OPRO_KEY的相同结果。基本上，如果每行只调用一次此函数（OPRO_KEY一次）就足够了，然后每周的结果将从该表更新。可以这样做吗？那么，不是每周都调用这个函数，而是每行调用一次，而且根据WEEKOFMONTH更新几周？

Answer 1

请尝试以下查询并检查效果

UPDATE  RM
SET     RM.WEEK_1   = (CASE WHEN WA.WEEKOFMONTH = 1 THEN WA.AVERAGE_AVAI ELSE RM.WEEK_1 END)
        ,RM.WEEK_2  = (CASE WHEN WA.WEEKOFMONTH = 2 THEN WA.AVERAGE_AVAI ELSE RM.WEEK_2 END)
        ,RM.WEEK_3  = (CASE WHEN WA.WEEKOFMONTH = 3 THEN WA.AVERAGE_AVAI ELSE RM.WEEK_3 END)
        ,RM.WEEK_4  = (CASE WHEN WA.WEEKOFMONTH = 4 THEN WA.AVERAGE_AVAI ELSE RM.WEEK_4 END)
        ,RM.WEEK_5  = (CASE WHEN WA.WEEKOFMONTH = 5 THEN WA.AVERAGE_AVAI ELSE RM.WEEK_5 END)
        ,RM.WEEK_6  = (CASE WHEN WA.WEEKOFMONTH = 6 THEN WA.AVERAGE_AVAI ELSE RM.WEEK_6 END)
FROM    @ROOMS_BY_DEPA_KEY1 RM
    OUTER APPLY(
        SELECT  P.AVERAGE_AVAI,P.WEEKOFMONTH
        FROM    dbo.f_SCAVAI_GetWeekAverage(RM.OPRO_KEY, @WEEKS_MONTH, @cWorkDaysOnly, RM.KAPACITETA) P 
    )   AS  WA

通过每行只减少一次函数调用次数来更新行

1 个答案: