sql(ms access):对于给定的记录,如何从给定的字段集中查询前5个值?

q9rjltbz  于 2021-08-09  发布在  Java
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我有一个包含几十个字段的表,其中18个是具有不同整数值的字段。我想为给定记录的五个具有最大值的字段提取字段名和相应的值。我将使用下表作为示例,其中我只想查询给定记录的两个最大值。

Name, FigureA, FigureB, FigureC
John, 40,      73,      81
Luke, 35,      21,      65

我想为约翰归还以下物品:

FigureB, 73
FigureC, 81

我已经走了这么远:

sSQL = "Select t.* " & _
            "From (Select 'A' as [FigureA], FigureA " & _
                    "From Table) as t " & _
            "Union All " & _
           "Select t.* " & _
            "From (Select 'B' as [FigureB], FigureB " & _
                    "From Table) as t " & _
            "Union All " & _
           "Select t.* " & _
            "From (Select 'C' as [FigureC], FigureC " & _
                    "From Table) as t"
bakd9h0s

bakd9h0s1#

在ms-access中,这可能是最简单的 union all :

select top (5) *
from (select t.*
      from (select top (1) "field1" as colname, max(field1) as max_val
            from t
           ) as t
      union all
      select t.*
      from (select top (1) "field2" as colname, max(field2)
            from t
           ) as t
      union all
      . . . 
     ) as t
order by max_val desc;

某些版本的ms access不支持 union allfrom 条款。该组件可能需要一个视图。

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