Reference one column more than once
SQL> create table product( 2 product_id integer primary key 3 ,price number(7,2) 4 ,description varchar2(75) 5 ,onhand number(5,0) 6 ,reorder number(5,0) 7 ,supplier_no integer 8 ); Table created. SQL> -- product Table Inserts: SQL> insert into product(product_id, price, description, onhand, reorder)values (1,2.50,'Happy Birthday',100,20); 1 row created. SQL> insert into product(product_id, price, description, onhand, reorder)values (2,23.00,'Happy Birthday',null,null); 1 row created. SQL> insert into product(product_id, price, description, onhand, reorder)values (3,null,'Happy New Year',null,null); 1 row created. SQL> insert into product(product_id, price, description, onhand, reorder)values (4,1.50,'Happy New Year',50,10); 1 row created. SQL> SQL> SQL> select description, price, price * .068 as tax, 2 price * 1.068 as "Total" 3 from product; DESCRIPTION --------------------------------------------------------------------------- PRICE TAX Total ---------- ---------- ---------- Happy Birthday 2.5 .17 2.67 Happy Birthday 23 1.564 24.564 Happy New Year Happy New Year 1.5 .102 1.602 4 rows selected. SQL> SQL> drop table product; Table dropped.