Where子句中的情况表达式

Question

我正在尝试在where子句中编写一个case表达式，但是我无法正确设置所需的语法。在where子句中，我要有case语句，请检查“ IndividualRateOption”列，然后根据该列将其添加到where子句中。

--- Get generic rates
            select  case when RateType = 'PRE' then 1
                         when RateType = 'RID' then 2
                         when RateType = 'QUL' then 3 end,
                    BillingEntityId,
                    @GroupID,
                    RateID,
                    TierItemId,
                    RateUnitType,
                    RateUnitValue,
                    RateType,
                    RateTypeEntityID,
                    EffectiveDate,
                    ExpirationDate,
                    Usage,
                    AgeFrom,
                    AgeTo,
                    Gender,
                    PayBrokerCommissions
              from #BillingEntityRates
             where case IndividualRateSelectionOption when 'ANV' then @AnniversaryDate between EffectiveDate and ExpirationDate
                    OR isnull(@AnniversaryDate,@MemberEligibilityDate) between EffectiveDate and ExpirationDate
                    and EntityId is null

如果IndividualRateSelectionOption为'ANV'，我想基于“ Effective和ExpirationDate之间的@anniversaryDate，而EntityId为null”进行过滤]

如果IndividualRateSelectionOption不是'ANV'，我想根据有效日期和有效日期之间的“ isnull（@ AnniversaryDate，@ MemberEligibilityDate）进行过滤并且EntityId为null“

以上是我到目前为止尝试过的，但是它在抱怨语法。在此先感谢。

Answer 1

当更简单的布尔逻辑起作用时，不要使用case：

where (IndividualRateSelectionOption = 'ANV' and 
       @anniversaryDate between Effective and ExpirationDate and
       EntityId is null
      ) or
      (IndividualRateSelectionOption <> 'ANV' and 
       coalesce(@AnniversaryDate, @MemberEligibilityDate) between EffectiveDate and ExpirationDate and
       EntityId is null
      )

您可以过滤掉EntityId is null逻辑：

where EntityId is null and
      ( (IndividualRateSelectionOption = 'ANV' and 
         @anniversaryDate between Effective and ExpirationDate          
        ) or
        (IndividualRateSelectionOption <> 'ANV' and 
         coalesce(@AnniversaryDate, @MemberEligibilityDate) between EffectiveDate and ExpirationDate and
        )
      )