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Monotone-Revision: 9054022ef1ca8aeba6e34842d27d9b94ce002b89 Monotone-Author: dev-unix.inverse.qc.ca Monotone-Date: 2006-06-15T19:34:10 Monotone-Branch: ca.inverse.sogo
199 lines
6.7 KiB
Python
Executable File
199 lines
6.7 KiB
Python
Executable File
#! /usr/bin/env python
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# advanced.py - demo of advanced features of PostGres. Some may not be ANSI.
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# inspired from the Postgres tutorial
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# adapted to Python 1995 by Pascal Andre
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print """
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__________________________________________________________________
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MODULE ADVANCED.PY : ADVANCED POSTGRES SQL COMMANDS TUTORIAL
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This module is designed for being imported from python prompt
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In order to run the samples included here, first create a connection
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using : cnx = advanced.DB(...)
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The "..." should be replaced with whatever arguments you need to open an
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existing database. Usually all you need is the name of the database and,
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in fact, if it is the same as your login name, you can leave it empty.
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then start the demo with: advanced.demo(cnx)
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__________________________________________________________________
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"""
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from pg import DB
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import sys
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# waits for a key
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def wait_key():
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print "Press <enter>"
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sys.stdin.read(1)
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# inheritance features
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def inherit_demo(pgcnx):
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print "-----------------------------"
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print "-- Inheritance:"
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print "-- a table can inherit from zero or more tables. A query"
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print "-- can reference either all rows of a table or all rows "
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print "-- of a table plus all of its descendants."
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print "-----------------------------"
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print
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print "-- For example, the capitals table inherits from cities table."
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print "-- (It inherits all data fields from cities.)"
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print
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print "CREATE TABLE cities ("
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print " name text,"
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print " population float8,"
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print " altitude int"
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print ")"
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print
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print "CREATE TABLE capitals ("
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print " state varchar(2)"
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print ") INHERITS (cities)"
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pgcnx.query("""CREATE TABLE cities (
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name text,
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population float8,
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altitude int)""")
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pgcnx.query("""CREATE TABLE capitals (
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state varchar(2)) INHERITS (cities)""")
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wait_key()
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print
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print "-- now, let's populate the tables"
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print
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print "INSERT INTO cities VALUES ('San Francisco', 7.24E+5, 63)"
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print "INSERT INTO cities VALUES ('Las Vegas', 2.583E+5, 2174)"
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print "INSERT INTO cities VALUES ('Mariposa', 1200, 1953)"
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print
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print "INSERT INTO capitals VALUES ('Sacramento', 3.694E+5, 30, 'CA')"
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print "INSERT INTO capitals VALUES ('Madison', 1.913E+5, 845, 'WI')"
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print
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pgcnx.query("INSERT INTO cities VALUES ('San Francisco', 7.24E+5, 63)")
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pgcnx.query("INSERT INTO cities VALUES ('Las Vegas', 2.583E+5, 2174)")
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pgcnx.query("INSERT INTO cities VALUES ('Mariposa', 1200, 1953)")
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pgcnx.query("INSERT INTO capitals VALUES ('Sacramento',3.694E+5,30,'CA')")
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pgcnx.query("INSERT INTO capitals VALUES ('Madison', 1.913E+5, 845, 'WI')")
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print
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print "SELECT * FROM cities"
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print pgcnx.query("SELECT * FROM cities")
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print "SELECT * FROM capitals"
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print pgcnx.query("SELECT * FROM capitals")
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print
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print "-- like before, a regular query references rows of the base"
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print "-- table only"
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print
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print "SELECT name, altitude"
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print "FROM cities"
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print "WHERE altitude > 500;"
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print pgcnx.query("""SELECT name, altitude
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FROM cities
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WHERE altitude > 500""")
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print
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print "-- on the other hand, you can find all cities, including "
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print "-- capitals, that are located at an altitude of 500 'ft "
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print "-- or higher by:"
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print
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print "SELECT c.name, c.altitude"
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print "FROM cities* c"
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print "WHERE c.altitude > 500"
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print pgcnx.query("""SELECT c.name, c.altitude
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FROM cities* c
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WHERE c.altitude > 500""")
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# arrays attributes
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def array_demo(pgcnx):
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print "----------------------"
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print "-- Arrays:"
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print "-- attributes can be arrays of base types or user-defined "
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print "-- types"
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print "----------------------"
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print
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print "CREATE TABLE sal_emp ("
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print " name text,"
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print " pay_by_quarter int4[],"
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print " pay_by_extra_quarter int8[],"
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print " schedule text[][]"
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print ")"
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pgcnx.query("""CREATE TABLE sal_emp (
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name text,
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pay_by_quarter int4[],
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pay_by_extra_quarter int8[],
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schedule text[][])""")
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wait_key()
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print
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print "-- insert instances with array attributes. "
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print " Note the use of braces"
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print
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print "INSERT INTO sal_emp VALUES ("
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print " 'Bill',"
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print " '{10000,10000,10000,10000}',"
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print " '{9223372036854775800,9223372036854775800,9223372036854775800}',"
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print " '{{\"meeting\", \"lunch\"}, {}}')"
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print
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print "INSERT INTO sal_emp VALUES ("
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print " 'Carol',"
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print " '{20000,25000,25000,25000}',"
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print " '{9223372036854775807,9223372036854775807,9223372036854775807}',"
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print " '{{\"talk\", \"consult\"}, {\"meeting\"}}')"
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print
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pgcnx.query("""INSERT INTO sal_emp VALUES (
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'Bill', '{10000,10000,10000,10000}',
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'{9223372036854775800,9223372036854775800,9223372036854775800}',
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'{{\"meeting\", \"lunch\"}, {}}')""")
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pgcnx.query("""INSERT INTO sal_emp VALUES (
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'Carol', '{20000,25000,25000,25000}',
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'{9223372036854775807,9223372036854775807,9223372036854775807}',
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'{{\"talk\", \"consult\"}, {\"meeting\"}}')""")
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wait_key()
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print
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print "----------------------"
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print "-- queries on array attributes"
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print "----------------------"
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print
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print "SELECT name FROM sal_emp WHERE"
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print " sal_emp.pay_by_quarter[1] <> sal_emp.pay_by_quarter[2]"
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print
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print pgcnx.query("""SELECT name FROM sal_emp WHERE
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sal_emp.pay_by_quarter[1] <> sal_emp.pay_by_quarter[2]""")
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print
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print pgcnx.query("""SELECT name FROM sal_emp WHERE
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sal_emp.pay_by_extra_quarter[1] <> sal_emp.pay_by_extra_quarter[2]""")
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print
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print "-- retrieve third quarter pay of all employees"
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print
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print "SELECT sal_emp.pay_by_quarter[3] FROM sal_emp"
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print
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print pgcnx.query("SELECT sal_emp.pay_by_quarter[3] FROM sal_emp")
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print
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print "-- retrieve third quarter extra pay of all employees"
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print
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print "SELECT sal_emp.pay_by_extra_quarter[3] FROM sal_emp"
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print pgcnx.query("SELECT sal_emp.pay_by_extra_quarter[3] FROM sal_emp")
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print
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print "-- retrieve first two quarters of extra quarter pay of all employees"
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print
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print "SELECT sal_emp.pay_by_extra_quarter[1:2] FROM sal_emp"
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print
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print pgcnx.query("SELECT sal_emp.pay_by_extra_quarter[1:2] FROM sal_emp")
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print
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print "-- select subarrays"
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print
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print "SELECT sal_emp.schedule[1:2][1:1] FROM sal_emp WHERE"
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print " sal_emp.name = 'Bill'"
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print pgcnx.query("SELECT sal_emp.schedule[1:2][1:1] FROM sal_emp WHERE " \
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"sal_emp.name = 'Bill'")
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# base cleanup
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def demo_cleanup(pgcnx):
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print "-- clean up (you must remove the children first)"
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print "DROP TABLE sal_emp"
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print "DROP TABLE capitals"
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print "DROP TABLE cities;"
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pgcnx.query("DROP TABLE sal_emp")
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pgcnx.query("DROP TABLE capitals")
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pgcnx.query("DROP TABLE cities")
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# main demo function
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def demo(pgcnx):
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inherit_demo(pgcnx)
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array_demo(pgcnx)
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demo_cleanup(pgcnx)
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