使用 CASE 语句名称作为另一个 CASE 语句中的另一个引用

Question

是否可以在 SQL 查询中的另一个 case 语句中引用另一个 case 语句名称？

示例：我有 3 个案例陈述。前 2 个 case 语句是 returning 基于关闭编码字段的值。我的第 3 个案例陈述我想将结束案例名称引用到 return 数量总和。

但是，我不知道如何让案例语句引用我之前创建的案例名称。我希望我能正确解释这一点。

如有任何帮助，我们将不胜感激。请参阅附图了解更多详情。

SELECT CI_ITEM.ITEMCODE
    , CI_ITEM.ITEMCODEDESC

    , CASE WHEN DATEDIFF("M",CI_ITEM.DATECREATED,GETDATE()) <60 THEN DATEDIFF("M",CI_ITEM.DATECREATED,GETDATE()) 
    ELSE 60 END AS NO_OF_MONTHS

    , CASE WHEN DATEDIFF("M",IM_ITEMTRANSACTIONHISTORY.TRANSACTIONDATE,GETDATE()) <=60 
    AND IM_ITEMTRANSACTIONHISTORY.TRANSACTIONCODE IN ('BI','II','SO','WI') 
    THEN IM_ITEMTRANSACTIONHISTORY.TRANSACTIONQTY *-1 ELSE '0' END AS QTY_CONSUMED_60_MONTHS

    , CASE WHEN NO_OF_MONTHS = 0 THEN 0 ELSE SUM([QTY_CONSUMED_60_MONTHS])/ [NO_OF_MONTHS] END AS MONTHLY_AVE_ON_60MONTHS_DATA

FROM CI_ITEM
INNER JOIN IM_ITEMTRANSACTIONHISTORY ON CI_ITEM.ITEMCODE = IM_ITEMTRANSACTIONHISTORY.ITEMCODE

Answer 1

只需将依赖案例包装在子查询中并将它们作为子查询结果的字段进行引用。

SELECT
    *,
     CASE WHEN NO_OF_MONTHS = 0 THEN 0 ELSE SUM([QTY_CONSUMED_60_MONTHS])/ [NO_OF_MONTHS] END AS MONTHLY_AVE_ON_60MONTHS_DATA
FROM
(
    SELECT CI_ITEM.ITEMCODE
        , CI_ITEM.ITEMCODEDESC

        , CASE WHEN DATEDIFF("M",CI_ITEM.DATECREATED,GETDATE()) <60 THEN DATEDIFF("M",CI_ITEM.DATECREATED,GETDATE()) 
        ELSE 60 END AS NO_OF_MONTHS

        , CASE WHEN DATEDIFF("M",IM_ITEMTRANSACTIONHISTORY.TRANSACTIONDATE,GETDATE()) <=60 
        AND IM_ITEMTRANSACTIONHISTORY.TRANSACTIONCODE IN ('BI','II','SO','WI') 
        THEN IM_ITEMTRANSACTIONHISTORY.TRANSACTIONQTY *-1 ELSE '0' END AS QTY_CONSUMED_60_MONTHS

    FROM CI_ITEM
    INNER JOIN IM_ITEMTRANSACTIONHISTORY ON CI_ITEM.ITEMCODE = IM_ITEMTRANSACTIONHISTORY.ITEMCODE
)AS X

使用 CASE 语句名称作为另一个 CASE 语句中的另一个引用

Using CASE statement name as another reference filed in another CASE statement

sql

case

case-statement

qsqlquery