Using The && Substitution Variable

Use the double-ampersand (&&) if you want to reuse the variable value without prompting the user each time.

SQL> select empno,ename,job,&&column_name from emp order by &column_name;

Enter value for column_name: sal

old   1: select empno,ename,job,&&column_name from emp order by &column_name

new   1: select empno,ename,job,sal from emp order by sal

    EMPNO ENAME      JOB             SAL

--------- ---------- --------- ---------

     7369 SMITH      CLERK           800

     7900 JAMES      CLERK           950

     7876 ADAMS      CLERK          1100

     7521 WARD       SALESMAN       1250

     7654 MARTIN     SALESMAN       1250

     7934 MILLER     CLERK          1300

     7844 TURNER     SALESMAN       1500

     7499 ALLEN      SALESMAN       1600

     7782 CLARK      MANAGER        2450

     7698 BLAKE      MANAGER        2850

     7566 JONES      MANAGER        2975

     7788 SCOTT      ANALYST        3000

     7902 FORD       ANALYST        3000

     7839 KING       PRESIDENT      5000

14 rows selected.

SQL> select empno,ename,job,&&column_name from emp order by &column_name; [IT DOES NOT PROMPT YOU FOR VALUE]

old   1: select empno,ename,job,&&column_name from emp order by &column_name

new   1: select empno,ename,job,sal from emp order by sal

    EMPNO ENAME      JOB             SAL

--------- ---------- --------- ---------

     7369 SMITH      CLERK           800

     7900 JAMES      CLERK           950

     7876 ADAMS      CLERK          1100

     7521 WARD       SALESMAN       1250

     7654 MARTIN     SALESMAN       1250

     7934 MILLER     CLERK          1300

     7844 TURNER     SALESMAN       1500

     7499 ALLEN      SALESMAN       1600

     7782 CLARK      MANAGER        2450

     7698 BLAKE      MANAGER        2850

     7566 JONES      MANAGER        2975

     7788 SCOTT      ANALYST        3000

     7902 FORD       ANALYST        3000

     7839 KING       PRESIDENT      5000

14 rows selected.