An overview of the main questions/design issues when starting to work with databases in Perl - choosing a database - matching DB datatypes to Perl datatypes - DBI architecture (handles, drivers, etc.) - steps of DBI interaction : prepare/execute/fetch - ORM principles and difficulties, ORMs on CPAN - a few examples with DBIx::DataModel - performance issues First given at YAPC::EU::2009 in Lisbon. Updated version given at FPW2011 in Paris and YAPC::EU::2011 in Riga

1. Working with databases in Perl Tutorial for FPW::2011, Paris [email_address] Département Office

3. Relational databases RDBMS = Relational Database Management System

4. Relational model join on c3 filter Table (rows + columns) projection c1 c2 c3 1 foo 1 2 foo 2 3 bar 1 c3 c4 1 xx 2 yy c1 c2 c3 c4 1 foo 1 xx 2 foo 2 yy 3 bar 1 xx

9. Writing SQL SQL is too low-level, I don't ever want to see it SQL is the most important part of my application, I won't let anybody write it for me

13. Perl DBI Basics

14. Architecture Database DBD driver DBI Object-Relational Mapper Perl program TIOOWTDI There is only one way to do it TAMMMWTDI There are many, many many ways to do it TIMTOWTDI There is more than one way to do it

22. Advanced Perl DBI

31. Object-Relational Mapping (ORM)

32. ORM Principle r1 r2 ... c1 c2 c3 ... c3 c4 +c1: String +c2: String +c3: class2 r1 : class1 RDBMS r2 : class1 Application table1 table2

37. Model (UML) Artist CD Track 1 * 1 *

42. Conclusion

44. Bonus slides

48. Modeling (UML) Author Distribution Module 1 * 1 * ► depends on * * ► contains

49. Terminology Author Distribution Module 1 * 1 * ► depends on * * ► contains multiplicity association name class association composition

50. Implementation author_id author_name e_mail 1 * 1 * * * Author distrib_id module_id Dependency distrib_id distrib_name d_release author_id Distribution module_id module_name distrib_id Module 1 1 link table for n-to-n association