How to merge two columns in DB2

Question

How can I merge two columns in a table and duplicate the others? Here is a simple example of what I want to do:

Suppose I have this table:

   | C1 | C2 |
--------------
A1 | 1  | 2  |
--------------
A1 | 3  | 4  |
--------------
A2 | 5  | 6  |

I want to transform it to the following result:

   | C  |
---------
A1 | 1  |
---------
A1 | 2  |
---------
A1 | 3  |
---------
A1 | 4  |
---------
A2 | 5  |
---------
A2 | 6  |

Is there a way to do this in SQL DB2 ?

Answer 1

you can simply use a union all

select A, C1 as C from `table`
union all 
select A, C2 from `table`