Question

我有一个包含ID，A，B，C，D，E ......列的表格（总共10个数字列）

对于每一行，我需要找到哪个列具有最大值，以及该值是什么。

E.G。这是我桌子的一排：
ID A B C D E F G H I J
XY 5 4 9 5 0 1 3 2 1 7

我想生成2个新列：
maxvalue，等于9，和 maxcol，等于“C”

除了大量的IF声明之外还有什么建议？

Answer 1

我没有可用的sql处理器，但是

的内容

select id , colName
from 
(select id, 'A' as colName, a as value union all
select id, 'B' as colName, b as value union all
select id, 'C' as colName, c as value union all
select id, 'D' as colName, d as value union all
select id, 'E' as colName, e as value union all
select id, 'F' as colName, f as value union all
select id, 'G' as colName, g as value union all
select id, 'H' as colName, h as value union all
select id, 'I' as colName, i as value union all
select id, 'J' as colName, j as value)
group by id having max(value)

Answer 2

使用unpivot的解决方案，假设您的表名为“TestTable”：

WITH unpivoted as 
(
    SELECT * FROM TestTable
    UNPIVOT
    (
        Val FOR Col IN (A, B, C, D, E, F, G, H, I, J)
    ) as u
),
maxvals as (
    SELECT ID, max(val) as MaxVal 
    FROM unpivoted
    GROUP BY ID
)
SELECT
    TestTable.*, 
    MaxVals.MaxVal, 
    (SELECT top 1 Col 
     FROM unpivoted 
     WHERE unpivoted.Id = TestTable.ID and Val = MaxVals.MaxVal) as MaxCol
FROM
    TestTable
    JOIN maxvals on maxvals.id = TestTable.Id

SQL：确定哪一列在每行中具有最大值

2 个答案: