IF Statement in Select

Question

I need to choose between value1 and value2 within a select statement.
TableA
Flag (char)
Value1
Value2
ItemDesc
pseudo code
select ItemDesc, (if Flag = 'y' then Value1 else Value2) as Price from TableA;
How can this be done?

Answer 1

select   itemdesc,
         sum (case
                 when flag = 'y'
                    then (case
                             when value1 < 10
                                then value1 * 1.2
                             else value1
                          end)
                 else value2
              end
             ) as price
    from tablea
group by itemdesc;