Sql 若表返回0行，则选择另一个查询

因为我的查询有时会返回0行，所以如果它返回0行，我需要选择另一个语句

select MR.NAME as NAMES,Isnull(cast(sum(MTTR/Month(getdate())) as decimal(18,2)),0) as YTDCURRENTYEAR from #Meantimeresult as MR 
 where YEAR(CONVERT(DATE, '01-' + Month)) = YEAR(GETDATE()) AND MONTH(CONVERT(DATE, '01-' + Month)) <= MONTH(GETDATE()) 
    group by MR.NAMES

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您可以使用公共表表达式包装第一个查询，并使用union all：

WITH CTE AS
(
    SELECT MR.NAME as NAMES, Isnull(cast(sum(MTTR/Month(getdate())) as decimal(18,2)),0) as YTDCURRENTYEAR 
    FROM #Meantimeresult as MR 
    WHERE YEAR(CONVERT(DATE, '01-' + Month)) = YEAR(GETDATE()) 
    AND MONTH(CONVERT(DATE, '01-' + Month)) <= MONTH(GETDATE()) 
    GROUP BY MR.NAMES
)

SELECT Names, YTDCURRENTYEAR
FROM CTE
UNION ALL
SELECT NAME='' ,YTDCURRENTYEAR=0
WHERE NOT EXISTS(
    SELECT 1 
    FROM CTE
)

---

如果您的查询是由c、vb、f、java等代码执行的，这种任务可以由代码以更简单的方式完成。@Srikanth。您应该提供示例数据、所需结果和逻辑解释。可能有一种更简单的方法来编写逻辑。

WITH CTE AS
(
    SELECT MR.NAME as NAMES, Isnull(cast(sum(MTTR/Month(getdate())) as decimal(18,2)),0) as YTDCURRENTYEAR 
    FROM #Meantimeresult as MR 
    WHERE YEAR(CONVERT(DATE, '01-' + Month)) = YEAR(GETDATE()) 
    AND MONTH(CONVERT(DATE, '01-' + Month)) <= MONTH(GETDATE()) 
    GROUP BY MR.NAMES
)

SELECT Names, YTDCURRENTYEAR
FROM CTE
UNION ALL
SELECT NAME='' ,YTDCURRENTYEAR=0
WHERE NOT EXISTS(
    SELECT 1 
    FROM CTE
)

IF NOT EXISTS (YOUR FIRST QUERY)
   BEGIN
      YOUR SECOND QUERY
   END