Where 子句 TSQL 中的 case 表達式

Question

我正在嘗試在 where 子句中編寫一個 case 表達式，但是我在為我想要做的事情找到正確的語法時遇到了麻煩。 在 where 子句中，我想讓 case 語句檢查列“IndividualRateOption”，並基於該列我想添加到 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 是'ANV'，我想根據“有效和到期日期之間的@anniversaryDate 和EntityId 為空”進行過濾

如果IndividualRateSelectionOption 不是'ANV'，我想根據EffectiveDate 和ExpirationDate 之間的“isnull(@AnniversaryDate,@MemberEligibilityDate) 和EntityId 為空”進行過濾

以上是我迄今為止嘗試過的，但它抱怨語法。 提前致謝。

Answer 1

不要使用case時，簡單的布爾邏輯的工作原理：

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
      )

您可以過濾掉EntityId is null邏輯：

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
        )
      )