First learn computer science and all the theory. Next develop a programming style. Then forget all that and just hack. George Carrette
The to_date function convert the string format date to the date format. When the developer want fetch the date format from the string, they can use to_date function. The DUAL table is a special one-row, one-column table present by default in Oracle and other database installations. The sysdate returns the current date from the oracle database server.
select to_date('2013/12/10', 'yyyy/mm/dd') from dual;