如果有多于x的Then Where语句

您可以将查询包装在另一个查询中 SELECT

SELECT *
FROM
(
    SELECT count(children) as ChildrenCount, nationality 
    FROM yourTable
    GROUP BY nationality 
) x
WHERE 
    (ChildrenCount > 3 AND nationality = 'Mexican')
    OR
    (ChildrenCount = 2 AND nationality = 'American')
    OR
    (ChildrenCount = 1 AND nationality = 'Japanese')

你想要的逻辑是什么?

让我猜一下,你想要有3个以上孩子的墨西哥人,想要有2个孩子的美国人,想要有1个孩子的日本人。在这种情况下,您希望:

having (case when count(nationality = 'Mexican' then children end) > 3 then 'true'
             when count(nationality = 'American' then children end) = 2 then 'true'
             when count(nationality = 'Japanese' then children end) = 1 then 'true'
        end) = 'true'

然而,即便如此,这似乎也很奇怪。你为什么数“孩子”。你在分组什么?如果子项只是数据中的一个字段,那么它应该是WHERE子句,而不是HAVING子句:

where (nationality = 'Mexican' and children end > 3) or
      (nationality = 'American' and children = 2) or
      (nationality = 'Japanese' and children = 1)

您可以将现有查询包装在CTE中,以将计数和分组与筛选分离,然后在带有CASE的最终WHERE子句中使用来自CTE的计数:

;WITH [Counts] AS
(
    SELECT
        ,nationality
        ,COUNT(children) AS [children]
    FROM
        xyz
    GROUP BY
        nationality
)
SELECT
    *
FROM
    [Counts]
WHERE 
    nationality = 
    (
        CASE 
            WHEN [children] > 3 THEN 'Mexican'
            WHEN [children] = 2 THEN 'American'
            WHEN [children] = 1 THEN 'Japanese' 
        END
    )

这应该有效

DECLARE @table TABLE     
(    
     nationality varchar (25),  
     totalchildren int
)   

insert @table  
    SELECT nationality,COUNT(children) AS totalchildren 
    FROM TABLENAME
    GROUP BY nationality

SELECT
    *
FROM
    @table  
WHERE 
    nationality = 
    (
        CASE 
            WHEN totalchildren > 3 THEN 'Mexican'
            WHEN totalchildren = 2 THEN 'American'
            WHEN totalchildren = 1 THEN 'Japanese' 
        END
    )