Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
Object Relation Mapping (ORM)

Another technical term? Yes - this one is a formal name for how you convert a database into Objects - applicable to any OO language (Perl, Python, PHP, Java ...)

Let's reduce it to basics.

* SQL Tables become object classes
* Table rows each become individual objects
* Individual columns become attributes.

OK - perhaps you've been doing it for years .... I know I have, though not so formalised. It's nice to have a buzzword now to impress people with! But there's more to it than that.

By writing code to formalise the conversion of data held in databases to objects, you can add a layer of abstraction and move the need to write SQL code within your application our to a separate module - very possibly a module that's already been written and placed on the CPAN or in the Cheeseshop or PEAR.

In Perl, there have been a number of ORM modules placed on the CPAN; the current "flavour of the month" is DBIx::Class. A year or two back, it was Class::DBI, which you'll still find in use on some legacy applications. Both DBIx::Class and Class::DBI rely on Tim Bunce's DBI module internally, so they can be used with the same wide variety of databases that DBI/DBD supports.




When you map a table onto a class, you'll note that your code repeats the definition of the column names in the Perl code (or Perl configuration file if you're being really good). But the programming axiom is "don't repeat anything" and if you're feeling REALLY clever, you can use DBIx::Class::Schema::Loader to pick it up from the database - as the cost of a little inefficiency in that the extra database enquiry is made every time you run your Perl. And THAT inefficiency can be prevented with dump_to_dir.
(written 2007-06-09, updated 2007-06-12)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
G997 - Well House Consultants - Newsletter Lead Articles
  [3202] Telling you something about us in just one line - (2011-03-15)
  [2743] Public Open Source Training Courses running this summer and autumn in Melksham - (2010-04-27)
  [2538] Open Source Training Centre and Courses for 2010 - (2009-12-16)
  [2425] Weekend and Christmas Promotion - Well House Manor Hotel, Melksham - (2009-09-26)
  [2370] C++, Python, and other training - do we use an IDE - (2009-08-21)
  [2253] Walks in and around Melksham, Wiltshire - (2009-06-21)
  [2119] Make your business a DESTINATION business - (2009-04-05)
  [2052] How was my web site compromised? - (2009-02-24)
  [1912] Book now for 2009 - (2008-11-29)
  [1819] Calling base class constructors - (2008-10-03)
  [1754] Upgrade from PHP 4 to PHP 5 - the TRY issue - (2008-08-15)
  [1663] Python in an afternoon - a lecture for experienced programmers - (2008-06-01)
  [1600] Cambidge - Tcl, Expect and Perl courses - (2008-04-04)
  [1545] Letting new visitors know we provide training courses - (2008-02-19)
  [1488] New trainee laptop fleet for our Open Source courses - (2007-12-30)
  [1386] New software product for warmblooded programmers - (2007-10-10)
  [1318] Well House Manor - feature comparison against the old place! - (2007-08-24)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [1065] Graham Ellis - an Introduction - (2007-02-05)
  [1000] One Thousand Posts and still going strong - (2006-12-18)

P308 - Using SQL Databases from Perl
  [3099] Perl - database access - DBD, DBI and DBIx modules - (2010-12-22)
  [2561] The future of MySQL - (2010-01-03)
  [2381] Checking the database connection manually - (2009-08-28)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [1885] Hiding a MySQL database behind a web page - (2008-11-15)
  [975] Answering ALL the delegate's Perl questions - (2006-12-09)
  [644] Using a MySQL database from Perl - (2006-03-13)
  [515] MySQL - an FAQ - (2005-12-03)

Q907 - Object Orientation and General technical topics - Object Orientation: Design Techniques
  [4098] Using object orientation for non-physical objects - (2013-05-22)
  [3978] Teaching OO - how to avoid lots of window switching early on - (2013-01-17)
  [3928] Storing your intermediate data - what format should you you choose? - (2012-11-20)
  [3887] Inheritance, Composition and Associated objects - when to use which - Python example - (2012-10-10)
  [3878] From Structured to Object Oriented Programming. - (2012-10-02)
  [3844] Rooms ready for guests - each time, every time, thanks to good system design - (2012-08-20)
  [3798] When you should use Object Orientation even in a short program - Python example - (2012-07-06)
  [3763] Spike solutions and refactoring - a Python example - (2012-06-13)
  [3760] Why you should use objects even for short data manipulation programs in Ruby - (2012-06-10)
  [3607] Designing your application - using UML techniques - (2012-02-11)
  [3454] Your PHP website - how to factor and refactor to reduce growing pains - (2011-09-24)
  [3260] Ruby - a training example that puts many language elements together to demonstrate the whole - (2011-04-23)
  [3085] Object Oriented Programming for Structured Programmers - conversion training - (2010-12-14)
  [3063] Comments in and on Perl - a case for extreme OO programming - (2010-11-21)
  [2977] What is a factory method and why use one? - Example in Ruby - (2010-09-30)
  [2953] Turning an exercise into the real thing with extreme programming - (2010-09-11)
  [2889] Should Python classes each be in their own file? - (2010-07-27)
  [2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
  [2865] Relationships between Java classes - inheritance, packaging and others - (2010-07-10)
  [2785] The Light bulb moment when people see how Object Orientation works in real use - (2010-05-28)
  [2747] Containment, Associative Objects, Inheritance, packages and modules - (2010-04-30)
  [2741] What is a factory? - (2010-04-26)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2523] Plan your application before you start - (2009-12-02)
  [2501] Simples - (2009-11-12)
  [2380] Object Oriented programming - a practical design example - (2009-08-27)
  [2327] Planning! - (2009-08-08)
  [2170] Designing a heirarcy of classes - getting inheritance right - (2009-05-11)
  [2169] When should I use OO techniques? - (2009-05-11)
  [1538] Teaching Object Oriented Java with Students and Ice Cream - (2008-02-12)
  [1528] Object Oriented Tcl - (2008-02-02)
  [1435] Object Oriented Programming in Perl - Course - (2007-11-18)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1047] Maintainable code - some positive advice - (2007-01-21)
  [836] Build on what you already have with OO - (2006-08-17)
  [831] Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13)
  [747] The Fag Packet Design Methodology - (2006-06-06)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [534] Design - one name, one action - (2005-12-19)
  [507] Introduction to Object Oriented Programming - (2005-11-27)
  [236] Tapping in on resources - (2005-03-05)
  [80] OO - real benefits - (2004-10-09)

Q908 - Object Orientation and General technical topics - Object Orientation: Design Patterns
  [4096] Perl design patterns example - (2013-05-20)
  [4021] Spike solution, refactored and reusable, Python - Example - (2013-02-28)
  [3843] Caching Design Patterns - (2012-08-20)
  [3810] Reading files, and using factories to create vectors of objects from the data in C++ - (2012-07-21)
  [3716] Learning C++ - a design pattern for your first class - (2012-05-02)
  [3608] Design Patterns - what are they? Why use them? - (2012-02-12)
  [2322] Looking for a practical standards course - (2009-08-05)
  [485] North, Norther and Northest - PHP 5 Objects - (2005-11-04)


Back to
Asda opening large new store in Melksham
Previous and next
or
Horse's mouth home
Forward to
Perl - functions for directory handling
Some other Articles
Some progress on the train campaign
Melksham businesses - networking together
Melksham Art Cafe
Perl - functions for directory handling
Object Relation Mapping (ORM)
Asda opening large new store in Melksham
Perl, the substitute operator s
Bathtubs and pecking birds
for loop - how it works (Perl, PHP, Java, C, etc)
Judging the quality of contributed Perl code
4300 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86 at 50 posts per page


This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2014: Well House Manor • 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • FAX: 01144 1225 899360 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/1224_Obj ... -ORM-.html • PAGE BUILT: Thu Sep 18 15:30:25 2014 • BUILD SYSTEM: WomanWithCat