MySQL greatest value in row?

Question

I\'m using MySQL with PHP. This is like my table: (I\'m using 3 values, but there are more)

id | 1 | 2 | 3
---+---+---+----
1  | 3 |12 |-29
2  | 5 |8  |8
3  | 99|7         


        

Answer 1

This query will return the max value regardless of NULLs

SELECT MAX(value)
FROM
(SELECT 1 column_no, col1 value
FROM anotherunamedtable
UNION ALL
SELECT 2, col2
FROM anotherunamedtable
UNION ALL
SELECT 3, col3
FROM anotherunamedtable) t

If you really need the column number then

SELECT id,
       (SELECT column_no
       FROM
              (SELECT 1 column_no, col1 value
              FROM anotherunamedtable
              WHERE id = t.id
              UNION ALL
              SELECT 2, col2
              FROM anotherunamedtable
              WHERE id = t.id
              UNION ALL
              SELECT 3, col3
              FROM anotherunamedtable
              WHERE id = t.id) s
        ORDER BY max_value DESC
        LIMIT 1)) as column_no
FROM anotherunamedtable t

But I think that the last query might perform exceptionally horrible. (Queries are untested)