Hi @Dinesh Singh,
If I understand correctly you need to select value which ever has non null out of two columns,
for instance if your data has this manner.
and you would like to select the data as (A1,B2,A3) you may use COALESCE(Col1,Col2,'<Your Default value>')
and on top of this table you may create a view so that end user directly view the result as single columns
NB: If you are convenient you may use case statement for complex logic implementation to retrieve as single column.