帶where / having子句的SQL查詢案例

Question

如何將Where或Haveing子句應用於查詢？ 我在Haveing子句中遇到問題。

DECLARE @dtDate DATE
SET @dtDate = GETDATE();

with EMS as
    (
       select * from ReportingView.WTA where FiscalMonth = DATENAME(MONTH, @dtDate) + ', ' +  DATENAME(YEAR, @dtDate) and ProductGroup = 'AAD'
    )

select 
       [ID]
      ,(CASE 
            WHEN Entitlements <= 0 THEN '0'
            ELSE CAST([Activations] as float) / [Entitlements]
        END) as Utilization 
from EMS
**HAVING  Utilization >= .25**

Answer 1

僅當您也使用GROUP BY時，才使用HAVING關鍵字。 您需要的是WHERE，但除非將其包裝在子選擇中，否則您將無法引用“利用率”。

Answer 2

在查詢的末尾都使用where和having子句。 如果你有兩個，那么where來了之前having 。

在你的情況，你having沒有工作，因為having只與所使用group by 。 having本質having是聚合值（例如sum ， count等）的where子句

---

例子：

WHERE

SELECT
    *
FROM
    EMS
WHERE
    Utilization >= 0.25

HAVING

SELECT
    col1, count(*)
FROM
    EMS
GROUP BY
    col1
HAVING
    count(*) > 10

HAVING WHERE

SELECT
    col1, count(*)
FROM
    EMS
WHERE
    Utilization >= 0.25
GROUP BY
    col1
HAVING
    count(*) > 10

---

編輯：此修改后的查詢應該為您工作。 我不確定為什么您的原始查詢使用的是CTE，但是我已經將case邏輯移到了CTE。

with EMS as
(
    select 
        [ID],
        (
            CASE 
                WHEN Entitlements <= 0 THEN '0'
                ELSE CAST([Activations] as float) / [Entitlements]
            END
        ) as Utilization 
    from
        ReportingView.WTA 
    where
        FiscalMonth = DATENAME(MONTH, @dtDate) + ', ' +  DATENAME(YEAR, @dtDate)
        and ProductGroup = 'AAD'
)
select
    *
from
    EMS
where
    Utilizaiton >= .25