I've just uploaded a neat little example - [here] from last week's Python course - it's amazing what you can do in a very few lines of code.

The application scenario is that we have a database of customers - some are residents at our hotel and others are delegates on our courses. Being mercenary folks, our accounting team wants to work out the income for a selection of customers ... and the algorithms are different for residents and delegates, even though many of the properties (a.k.a. attributes) of both groups (a.k.a. subclasses) of customer are handled identically.

Some interesting features of the demo ...

• I have used SqLite as my database engine. For small to medium sized database requirements, SqLite is excellent and growing. It's shipped with modern versions of Python, it's good, and it avoids the need for an extra level of process - a database daemon - that you'll get with MySQL or Oracle. The database can be accessed from "any" language - not just Python - and it transactional across concurrent applications (which other daemonless databases are not).

• As records are read off the database, the may pertain to either customer type - and I have used a static factory method to build my new objects, allowing me to simply pass in the data from the database to a piece of code that's maintained with the classes themselves and have it return a new customer object of the appropriate subtype. There is no need for my main application (and it would not be desirable) to get involved in the detail of working out what type of customer each record pertains to as it comes off the database.

(written 2010-05-29, updated 2010-06-02)

 Y115 - Additional Python Facilities
  [3469] Teaching dilemma - old tricks and techniques, or recent enhancements? - (2011-10-08)
  [3442] A demonstration of how many Python facilities work together - (2011-09-16)
  [3089] Python regular expressions - repeating, splitting, lookahead and lookbehind - (2010-12-17)
  [2790] Joining a MySQL table from within a Python program - (2010-06-02)
  [2765] Running operating system commands from your Python program - (2010-05-14)
  [2764] Python decorators - your own, staticmethod and classmethod - (2010-05-14)
  [2746] Model - View - Controller demo, Sqlite - Python 3 - Qt4 - (2010-04-29)
  [2745] Connecting Python to sqlite and MySQL databases - (2010-04-28)
  [2721] Regular Expressions in Python - (2010-04-14)
  [2655] Python - what is going on around me? - (2010-02-28)
  [2462] Python - how it saves on compile time - (2009-10-20)
  [2435] Serialization - storing and reloading objects - (2009-10-04)
  [2407] Testing code in Python - doctest, unittest and others - (2009-09-16)
  [1876] Python Regular Expressions - (2008-11-08)
  [1337] A series of tyre damages - (2007-09-08)
  [1336] Ignore case in Regular Expression - (2007-09-08)
  [1305] Regular expressions made easy - building from components - (2007-08-16)
  [1149] Turning objects into something you can store - Pickling (Python) - (2007-04-15)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [1043] Sending an email from Python - (2007-01-18)
  [901] Python - listing out the contents of all variables - (2006-10-21)
  [753] Python 3000 - the next generation - (2006-06-09)
  [672] Keeping your regular expressions simple - (2006-04-05)
  [663] Python to MySQL - (2006-03-31)
  [463] Splitting the difference - (2005-10-13)
  [239] What and why for the epoch - (2005-03-08)
  [208] Examples - Gadfly, NI Number, and Tcl to C interface - (2005-02-10)
  [183] The elegance of Python - (2005-01-19)

S200 - MySQL - SQLite
  [3269] Files or Databases? MySQL, SQLite, or Oracle? - (2011-04-28)
  [3139] Steering our Python courses towards wxPython, SQLite and Django - (2011-01-19)
  [3099] Perl - database access - DBD, DBI and DBIx modules - (2010-12-22)
  [2744] PyQt (Python and Qt) and wxPython - GUI comparison - (2010-04-28)
  [2561] The future of MySQL - (2010-01-03)

S151 - Introduction to SQL and MySQL
  [2567] Extra MySQL course dates (2 day course, UK) - (2010-01-08)
  [2134] Oracle take over Sun who had taken over MySQL - (2009-04-21)
  [924] The LAMP Cookbook - Linux, Apache, MySQL, PHP / Perl - (2006-11-13)
  [918] Databases needn't be frightening, hard or expensive - (2006-11-08)
  [691] Testing you Perl / PHP / MySQL / Tcl knowledge - (2006-04-19)
  [591] Key facts - SQL and MySQL - (2006-02-04)
  [515] MySQL - an FAQ - (2005-12-03)
  [444] Database or Progamming - which to learn first? - (2005-09-13)
  [382] Central London Courses - Perl, PHP, Python, Tcl, MySQL - (2005-07-18)
  [175] Worthwhile - (2005-01-11)
  [85] Present and future MySQL - (2004-10-12)
  [84] MySQL - nuggets - (2004-10-11)

Y113 - Python and SQL databases
  [3136] A framework with python - Django - first steps - (2011-01-17)

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Cost of Sales
Sleeping in on Sunday
Factory methods and SqLite in use in a Python teaching example
The Light bulb moment when people see how Object Orientation works in real use
Course Lunches
The Perl Survey
Tell the Melksham Chamber or you only have yourself to blame
The 500 pound question to get you started