select 'c1' as Column1, c1 as Column2 from tbl where c1 is not null union all select 'c2', c2 from tbl where c2 is not null union all select 'c3', c3 from tbl where c3 is not null union all select 'c4', c4 from tbl where c4 is not null
select 'c1' as Column1, c1 as Column2 from tbl where c1 is not null union all select 'c2', c2 from tbl where c2 is not null union all select 'c3', c3 from tbl where c3 is not null union all select 'c4', c4 from tbl where c4 is not null