Oracle : select maximum value from different columns of the same row

Question

The whole question is pretty much in the title. For each row of the table I\'d like to select the maximum of a subset of columns.

For example, from this table

Answer 1

Use GREATEST but also handle possible NULL's

SELECT name, GREATEST(NVL(m1,0), NVL(m2,0), NVL(m3,0), NVL(m4,0)) AS "Max"
FROM yourtable

Input:

name m1 m2 m3 m4
A    1  2  3  4
B    6  3  4  5
C    1  5  2  1

Output:

NAME Max
A    4
B    6
C    5

SQL Fiddle: http://sqlfiddle.com/#!4/ae268/7/0

Input:

name m1 m2   m3 m4
A    1  2    3  null
B    6  null 4  5
C    1  5    2  1

Output:

NAME Max
A    3
B    6
C    5

SQL Fiddle: http://sqlfiddle.com/#!4/b1c46/1/0