Postgres95 1.01 Distribution - Virgin Sources

src/tutorial/advanced.source

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+---------------------------------------------------------------------------
+--
+-- advanced.sql-
+--    more POSTGRES SQL features. (These are not part of the SQL-92
+--    standard.)
+--
+--
+-- Copyright (c) 1994, Regents of the University of California
+--
+-- $Id: advanced.source,v 1.1.1.1 1996/07/09 06:22:34 scrappy Exp $
+--
+---------------------------------------------------------------------------
+
+-----------------------------
+-- 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,
+	altitude	int		-- (in ft)
+)
+
+CREATE TABLE capitals (
+	state		char2
+) 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;
+
+
+-----------------------------
+-- Time Travel:
+--	this feature allows you to run historical queries. 
+-----------------------------
+
+-- first, let's make some changes to the cities table (suppose Mariposa's
+-- population grows 10% this year)
+
+UPDATE cities
+SET population = population * 1.1
+WHERE name = 'Mariposa';
+
+-- the default time is the current time ('now'):
+
+SELECT * FROM cities WHERE name = 'Mariposa';
+
+-- we can also retrieve the population of Mariposa ever has. ('epoch' is the
+-- earliest time representable by the system)
+
+SELECT name, population
+FROM cities['epoch', 'now']	-- can be abbreviated to cities[,]
+WHERE name = 'Mariposa';
+
+
+----------------------
+-- Arrays:
+--      attributes can be arrays of base types or user-defined types
+----------------------
+
+CREATE TABLE sal_emp (
+	name	text,
+	pay_by_quarter	int4[],
+	schedule	char16[][]
+);
+
+-- insert instances with array attributes.  Note the use of braces
+
+INSERT INTO sal_emp VALUES (
+	'Bill',
+	'{10000,10000,10000,10000}',
+	'{{"meeting", "lunch"}, {}}')
+
+INSERT INTO sal_emp VALUES (
+	'Carol',
+	'{20000,25000,25000,25000}',
+	'{{"talk", "consult"}, {"meeting"}}');
+
+----------------------
+-- queries on array attributes
+----------------------
+SELECT name FROM sal_emp WHERE
+	sal_emp.pay_by_quarter[1] <> sal_emp.pay_by_quarter[2];
+
+-- retrieve third quarter pay of all employees
+
+SELECT sal_emp.pay_by_quarter[3] FROM sal_emp;
+
+-- select subarrays
+
+SELECT sal_emp.schedule[1:2][1:1] FROM sal_emp WHERE	
+	sal_emp.name = 'Bill';
+
+
+-- clean up (you must remove the children first)
+DROP TABLE sal_emp
+DROP TABLE capitals
+DROP TABLE cities;