Combine columns from same table

Hi Guys,

I have a table with the following information:
ID; A; B; C
1; A; B; C
2; A; B; C
3; A; B; C

I want to turn these into the following table:
1; A
1; B
1; C
2; A
2; B
2; C

After googeling for a couple of hours, i can't seem to find the solution. Is there a easy solution to this?

Thank you in advance!

With kind regards,

Jeroni Jamboni