HOWTO Select Several Rows In One Comma- Separated

Hello!!

First of all, thank you in advance for helping me!!!

My problem is that I have a BBDD with a table like this (in Oracle and in MySql, both)

E.g.

+---------+-----------+
| groupId | serviceId |
+---------+-----------+
| grup1 | service1 |
| grup1 | service2 |
| grup1 | service3 |
| grup2 | service1 |
| grup2 | service2 |
+---------+-----------+

And I need to do a select o a procedure or something that returns me something like this:

+---------+------------------------------------------+
| groupId | serviceId |
+---------+------------------------------------------+
| grup1 | service1, service2, service3 |
+---------+------------------------------------------+

Is this possible in any way????

Than you very very much.

Almu