Transpose a query output

Question

I have a normal select query which results following output.

select cid,x1,x2,x3,x4,fy
  from temp_table;

cid     x1  x2  x3  x4  fy
-----------------------         


        

Answer 1

Here is a way to do this with just subqueries and aggregation:

select name,
       sum(case when fy = 2014 then x end) as "2014",
       sum(case when fy = 2015 then x end) as "2015",
       sum(case when fy = 2016 then x end) as "2016"
from (select fy,
             (case when n.n = 1 then 'x1'
                   when n.n = 2 then 'x2'
                   when n.n = 3 then 'x3'
                   when n.n = 4 then 'x4'
              end) as name,
             (case when n.n = 1 then x1
                   when n.n = 2 then x2
                   when n.n = 3 then x3
                   when n.n = 4 then x4
              end) as x
      from temp_table cross join
            (select 1 as n from dual union all
             select 2 from dual union all
             select 3 from dual union all
             select 4 from dual
            ) n
     ) t
group by name;

You can also use pivot, but that is a very recent addition to Oracle SQL, so I'm inclined to use this method.