Question

目前我有9列

Brand, ID, M, T, W, Th, Fri, Sat, Sun
abc, 1, 2, 4, 6, 3, 7, 1,  5

我想找出以下哪些群体的个人数量最多。 m / t / w / th，fri，sat / sun。例如，在上表中，将选择星期五，因为它具有最高计数。

Answer 1

假设值中没有关系，您可以使用greatest和case表达式执行此操作。如果存在关联，则会返回case表达式中遇到的第一个值（在关联天数内）。

select case greatest(M, T, W, Th, Fri, Sat, Sun) 
            when M then 'Monday'
            when T then 'Tuesday'
            when W then 'Wednesday'
            when Th then 'Thursday'
            when Fri then 'Friday'
            when Sat then 'Saturday'
            when Sun then 'Sunday'
        end 
from tbl

Answer 2

SELECT BRAND, ID, GREATEST (M, T, W, Th, Fri, Sat, Sun) Max_day
FROM yourtable;

Answer 3

select brand, ID,

case 
    when M>T and M>W and M>Th and M>Fri and M>Sat and M>Sun then M
    when T>M and T>W and T>Th and T>Fri and T>Sat and T>Sun then T
    when W>T and W>M and W>Th and W>Fri and W>Sat and W>Sun then W
    when TH>T and TH>W and TH>M and TH>Fri and TH>Sat and TH>Sun then TH
    when FRI>T and FRI>W and FRI>Th and FRI>M and FRI>Sat and FRI>Sun then FRI
    when SAT>T and SAT>W and SAT>Th and SAT>Fri and SAT>M and SAT>Sun then SAT
    when SUN>T and SUN>W and SUN>Th and SUN>Fri and SUN>Sat and SUN>M then SUN
ELSE M END AS MAXDAY

FROM TBL1;

MySQL从一组列中查找最大计数

3 个答案: