的MySQL尋找從一組列

Question

的最大數目前我有9列

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

我想找出以下組的具有最高單獨計數。 m/t/w/th，星期五，星期六/星期日。例如在上表中，星期五將被選中，因爲它具有最高的計數。

Answer 1

假設值沒有關係，可以用greatest和case表達式來做到這一點。如果有關係，則會返回case表達式中遇到的第一個值（在連續的幾天之內）。

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;