SQL NATURAL JOIN .

SQL using NATURAL JOIN.

• NATURAL JOIN - Works only when the two tables have a single identical named and type column as the joining key.
• NATURAL JOIN is nearly the same as INNER JOIN except that repeated column is avoided.
• When using NATURAL JOIN, the ON and USING keywords should not be allowed, even for some system you can.
• Not every RDBMS has implemented NATURAL JOIN.
• A skeleton version of NATURAL JOIN syntax is this:

  SELECT select_list
  FROM table_1 
  NATURAL JOIN table_2
  [WHERE search_conditions ]
  [ORDER BY column1, column2, ... ]

  Example using NATURAL JOIN between the tables:
  SQL server does not support NATURAL JOIN.
  MySQL, Oracle, PostgreSQL :

  Select First_name "First name",
    Last_name "Last name",
    email, Telephone_type "Phone type",
    Telephone_number as "Phone number"
   from customers 
   NATURAL JOIN telephones 
   WHERE  Telephone_type<>'Unknown'
   order by Last_name;
   

  The result should be:

  First name	Last name	email	Phone type	Phone number
  Judith	Bowman	J.Bowman@imb.com	Cell	(371) 153-54
  Judith	Bowman	J.Bowman@imb.com	Work	(371) 143-54
  Ricard	Nixon	Ricard.Nixon@hotmail.com	Work	(978) 667-94
  Ricard	Nixon	Ricard.Nixon@hotmail.com	Home	(978) 667-94
  Robert	Redford	R.Redford@google.com	Home	(679) 234-94