Три столбца - получите MAX с SQL

Ответ 1

В MySQL вы можете использовать GREATEST Функция:

SELECT  MAX(GREATEST(one, two, three))
FROM    T;

Пример скрипта SQL

Ответ 2

SELECT MAX(field) FROM (
    SELECT one AS field FROM table
    UNION 
    SELECT two AS field FROM table
    UNION 
    SELECT three AS field FROM table
) AS t

Ответ 3

select GREATEST(max(one), max(two), max(three)) as maximum 
from table;

Ответ 4

Вы можете отключить данные, подобные этому:

select max(value)
from
(
  select id, 'one' col, one value
  from yourtable
  union all
  select id, 'two' col, two value
  from yourtable
  union all
  select id, 'three' col, three value
  from yourtable
) src

Смотрите SQL Fiddle with Demo.

Или вы можете использовать что-то вроде этого:

SELECT max(data)
FROM 
(
  SELECT 
    CASE s.col
      WHEN 'one' THEN one
      WHEN 'two' THEN two
      WHEN 'three' THEN three
    END AS DATA
  FROM yourtable t
  CROSS JOIN 
  (
    SELECT 'one' AS col
    UNION ALL SELECT 'two'
    UNION ALL SELECT 'three'
  ) s
) s

См. SQL Fiddle with Demo

Ответ 5

Попробуйте этот запрос

SELECT tempTable.id, tempTable.max(val) 
FROM (SELECT id, max(one) AS val
      FROM tbl 
      UNION 
      SELECT id, max(two) AS val
      FROM tbl 
      UNION 
      SELECT id, max(three) AS val
      FROM tbl
) AS tempTable;

Ответ 6

select max( if( one > two, if( one > three, one, three ), if( two > three, two, three ) )
  from Rating

Ответ 7

Вы можете использовать оператор case

SELECT
    CASE
        WHEN one >= two AND one >= three THEN one
        WHEN two >= one AND two >= three THEN two
        WHEN three >= one AND three >= two THEN three
        ELSE one
    END AS MaxVal