SQL Query to Convert Rows into Columns

We can accomplish this by a "pivot" query. Please look at the small testcase.

SQL> desc t1
 Name Null? Type
 --------------- -------- ----------------
 NAME VARCHAR2(10)
 YEAR NUMBER(4)
 VALUE NUMBER(4)

SQL>
SQL> select * from t1;

NAME YEAR VALUE
---------- ---------- ----------
john 1991 1000
john 1992 2000
john 1993 3000
jack 1991 1500
jack 1992 1200
jack 1993 1340
mary 1991 1250
mary 1992 2323
mary 1993 8700

9 rows selected.

SQL> -- now, try out the pivot query
SQL> select year,
  2 max( decode( name, 'john', value, null ) ) "JOHN",
  3 max( decode( name, 'jack', value, null ) ) "JACK",
  4 max( decode( name, 'mary', value, null ) ) "MARY"
  5 from
  6 (
  7 select name, year, value
  8 from t1
  9 )
 10 group by year ;

      YEAR JOHN JACK MARY
---------- ---------- ---------- ----------
      1991 1000 1500 1250
      1992 2000 1200 2323
      1993 3000 1340 8700

Source:http://p2p.wrox.com/oracle/11931-sql-query-convert-columns-into-rows.html
Source:http://www.club-oracle.com/forums/pivoting-row-to-column-conversion-techniques-sql-t144/