---------------------------------------------------------------------------
--
-- advanced.sql-
--    Tutorial on advanced more PostgreSQL features
--
--
-- Copyright (c) 1994, Regents of the University of California
--
-- $Id: advanced.source,v 1.1.1.1 2002/02/07 17:57:59 bpalmer Exp $
--
---------------------------------------------------------------------------

-----------------------------
-- Inheritance:
--	S table can inherit from zero or more tables.  A query can reference
--	either all rows of a table or all rows of a table plus all of its
--	descendants.
-----------------------------

-- For example, the capitals table inherits from cities table. (It inherits 
-- all data fields from cities.)

CREATE TABLE cities (
	name		text,
	population	float8,
	altitude	int		-- (in ft)
);

CREATE TABLE capitals (
	state		char(2)
) INHERITS (cities);

-- Now, let's populate the tables.
INSERT INTO cities VALUES ('San Francisco', 7.24E+5, 63);
INSERT INTO cities VALUES ('Las Vegas', 2.583E+5, 2174);
INSERT INTO cities VALUES ('Mariposa', 1200, 1953);

INSERT INTO capitals VALUES ('Sacramento', 3.694E+5, 30, 'CA');
INSERT INTO capitals VALUES ('Madison', 1.913E+5, 845, 'WI');

SELECT * FROM cities;
SELECT * FROM capitals;

-- like before, a regular query references rows of the base table only

SELECT name, altitude
FROM cities
WHERE altitude > 500;

-- on the other hand, you can find all cities, including capitals, that
-- are located at an altitude of 500 'ft or higher by:

SELECT c.name, c.altitude
FROM cities* c
WHERE c.altitude > 500;


-- clean up (you must remove the children first)
DROP TABLE capitals;
DROP TABLE cities;
