create table tb_user as select ename from scott.emp
/

Table created.

 ---------------------------------------------
 
SELECT q1.r1, q1.ename, q2.ename
  FROM (SELECT t.ename, ROWNUM r1
          FROM (SELECT DISTINCT ename
                           FROM tb_user) t) q1,
       (SELECT t.ename, ROWNUM r2
          FROM (SELECT DISTINCT ename
                           FROM tb_user) t) q2
 WHERE q1.r1 = q2.r2(+) -  1 
 --------------------------------------------
 
        R1 ENAME      ENAME
 ---------- ---------- ----------
 
          1  ADAMS      ALLEN
          2  ALLEN      BLAKE
          3  BLAKE      CLARK
          4  CLARK      FORD
          5  FORD       JAMES
          6  JAMES      JONES
          7  JONES      KING
          8  KING       MARTIN
          9  MARTIN     MILLER
         10  MILLER     SCOTT
         11  SCOTT      SMITH
         12  SMITH      TURNER
         13  TURNER     WARD
         14  WARD

 14  rows selected.