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 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
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