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---------------------------------------------------------------------------
--
-- advanced.sql-
-- Tutorial on advanced PostgreSQL features
--
--
-- Copyright (c) 1994, Regents of the University of California
--
-- src/tutorial/advanced.source
--
---------------------------------------------------------------------------
-----------------------------
-- Inheritance:
-- A 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,
elevation 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;
-- You can find all cities, including capitals, that
-- are located at an elevation of 500 ft or higher by:
SELECT c.name, c.elevation
FROM cities c
WHERE c.elevation > 500;
-- To scan rows of the parent table only, use ONLY:
SELECT name, elevation
FROM ONLY cities
WHERE elevation > 500;
-- clean up (you must remove the children first)
DROP TABLE capitals;
DROP TABLE cities;
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