How to retrieve two columns data in A,B format in Oracle

Question

I have two columns in oracle database

+---------+---------+
| Column1 | Column2 |
+---------+---------+
| A       | 1       |
| A       | 2       |
+--------         


        

Answer 1

All abow answers are correct and I want to add one case to solve small problem. In my case my_column1 type was nvarchar2 but text was number and the bellow code does not work and display me only whitespace:

select group_id, listagg( t.my_column1 || '-' || to_char(t.doc_date,'dd.mm.yyyy') ||  ' ') within group(order by doc_date) 
 from my_table t
 group by group_id

when I wrote like this it works.

select group_id, listagg( to_char(t.my_column1) || '-' || to_char(t.doc_date,'dd.mm.yyyy') ||  ' ') within group(order by doc_date) 
 from my_table t
 group by group_id

I hope my feedback would save someone's time