使用row_number分析函数行列转换

create table test_abcd(a int,b int,c varchar2(100));
insert into test_abcd values(1,2,'abced');
insert into test_abcd values(1,2,'efg');
insert into test_abcd values(1,2,'hig');
insert into test_abcd values(3,2,'hig');
insert into test_abcd values(3,2,'eiw');
select * from test_abcd

select a, b, max(first_name), max(sec_name), max(third_name)
  from (select a,
               b,
               decode(row_cnt, 1, c) first_name,
               decode(row_cnt, 2, c) sec_name,
               decode(row_cnt, 3, c) third_name
          from (select a,
                       b,
                       c,
                       row_number() over(partition by a, b order by c) row_cnt
                  from test_abcd) s)
 group by a, b;