
Example:
dbadmin=> SELECT * FROM test ORDER BY group_id;
group_id | name
----------+---------
1 | ANDRIUS
1 | DAVE
1 | JIM
1 | KRISTEN
2 | BRYAN
2 | SCOTT
3 | CURTIS
3 | LENOY
3 | ROBERT
4 | CARLOS
4 |
(11 rows)
dbadmin=> SELECT LISTAGG(name) FROM test;
LISTAGG
-----------------------------------------------------------------
ANDRIUS,DAVE,JIM,KRISTEN,BRYAN,SCOTT,CURTIS,LENOY,ROBERT,CARLOS
(1 row)
dbadmin=> SELECT group_id, LISTAGG(name) FROM test GROUP BY group_id ORDER BY group_id;
group_id | LISTAGG
----------+--------------------------
1 | ANDRIUS,DAVE,JIM,KRISTEN
2 | BRYAN,SCOTT
3 | CURTIS,LENOY,ROBERT
4 | CARLOS
(4 rows)
Have fun!