I have following table:
with tbl as (select 1 col1, 'a' col2 from dual
union select 2 , 'a' from dual
union select 3 , 'b' from dual
union select 4 , 'a' from dual
union select 5 , 'a' from dual
union select 6 , 'b' from dual
union select 7 , 'b' from dual
) select * from tbl order by col1;
I want following result i.e first value from col2 whenever col2 value changes.
1 ,a
3 ,b
4 ,a
6 ,b
How can I do this in SQL using analytical function