conn / as sysdba

CREATE TABLESPACE test DATAFILE '+DATA_DG';

DROP TABLESPACE test INCLUDING CONTENTS AND DATAFILES;

CREATE USER test IDENTIFIED BY test DEFAULT TABLESPACE test TEMPORARY TABLESPACE temp QUOTA UNLIMITED ON test;

GRANT CONNECT, RESOURCE TO test;

conn test/test

--choose D
INSERT INTO max_data (cola, colb,colc, cold) VALUES (1,4,5,6);

--choose B
INSERT INTO max_data (cola, colb,colc, cold) VALUES (2,8,1,2);

--choose A
INSERT INTO max_data (cola, colb,colc, cold) VALUES (9,8,7,6);

--choose C
INSERT INTO max_data (cola, colb,colc, cold) VALUES (6,8,10,9);

SELECT * FROM max_data;

TEST@ORCL1>SELECT rownum, a.* FROM (SELECT cola, colb,colc, cold FROM max_data ORDER BY colc desc)a WHERE rownum=1;

    ROWNUM       COLA       COLB       COLC       COLD
---------- ---------- ---------- ---------- ----------
         1          6          8         10          9

SQL> INSERT INTO max_data (cola, colb,colc, cold) VALUES (1,4,5,6);
INSERT INTO max_data (cola, colb,colc, cold) VALUES (1,4,5,6)
            *
ERROR at line 1:
ORA-00942: table or view does not exist

create table max_data (cola number, colb number,colc number, cold number);

SQL> col what_column format a10
SQL> With max_data As
  2  ( Select 1 ident, 1 cola, 4 colb,  5 colc, 6 cold From dual Union all --D
  3    Select 2 ident, 2 cola, 8 colb,  1 colc, 2 cold From dual Union all --B
  4    Select 3 ident, 9 cola, 8 colb,  7 colc, 6 cold From dual Union all --A
  5    Select 4 ident, 6 cola, 8 colb, 10 colc, 9 cold From dual           --C
  6  )
  7  SELECT ident
  8       , Case Greatest(cola, colb, colc, cold)
  9         When cola Then 'COLA'
 10         When colb Then 'COLB'
 11         When colc Then 'COLC'
 12         When cold Then 'COLD'
 13         End what_column
 14      , Greatest(cola, colb, colc, cold) what_value
 15  FROM   max_data
 16  /

     IDENT WHAT_COLUM WHAT_VALUE
---------- ---------- ----------
         1 COLD                6
         2 COLB                8
         3 COLA                9
         4 COLC               10

SQL>

A B C D
1,4,5,6
2,8,1,2
9,8,7,6
6,8,10,9

--result should be as follow
D
B
A
C

A B C D
1,4,5,6
2,8,1,2
9,8,7,6
6,8,10,9
6,8,9,10

--result should be as follow
D
B
A
C
D

A B C D
1,4,5,6
2,8,1,2
9,8,7,6
6,8,9,10


results
D
B
A
D

a b c d
1 1 1 1
result
a

e.g

A B C D
1,4,5,6
2,8,1,2
9,8,7,6
6,8,10,9
1,1,,1,1

result
D
B
A
C
A

SQL> select d.*, 
  2         decode(greatest(cola,colb,colc,cold), cola,'A', colb,'B', colc,'C', cold,'D') res
  3  from max_data d
  4  /
      COLA       COLB       COLC       COLD R
---------- ---------- ---------- ---------- -
         1          4          5          6 D
         2          8          1          2 B
         9          8          7          6 A
         6          8         10          9 C