oracle update each distinct row with new value

Question

value    group
-----------------
value2a, value2
value2b, value2
value2c, value2
value3a, value3
value3b, value3
value3c, value3
value3d, value3
value4a, value4
value4b, value4
value4c, value4
value4d, value4
value5a, value5
value5b, value5
value5c, value5

How can I UPDATE table1 so that my script basically runs through every line and changes 'group' to something like

group-1
group-2
group-3
group-4
group=5

instead of

value1
value2
value3
value4
value5

If I can get the distinct values with this simple qquery

SELECT DISTINCT group FROM table1;

I must then be able to do some sort of

UPDATE table1 SET group = CONCAT('group-',rownum) WHERE group = ....

Answer 1

Can you just do this:

UPDATE table1 SET group = REPLACE(t.group, 'value', 'group-')

Reference:

REPLACE