DBI::FAQ 1.52

DBI::FAQ is a Perl module for the Frequently Asked Questions of the Perl5 Database Interface.

What is DBI, DBperl, Oraperl and *perl?

To quote Tim Bunce, the architect and author of DBI:

``DBI is a database access Application Programming Interface (API)
for the Perl Language. The DBI API Specification defines a set
of functions, variables and conventions that provide a consistent
database interface independant of the actual database being used.

In simple language, the DBI interface allows users to access multiple database types transparently. So, if you connecting to an Oracle, Informix, mSQL, Sybase or whatever database, you dont need to know the underlying mechanics of the 3GL layer. The API defined by DBI will work on all these database types.

A similar benefit is gained by the ability to connect to two different databases of different vendor within the one perl script, ie, I want to read data from an Oracle database and insert it back into an Informix database all within one program. The DBI layer allows you to do this simply and powerfully.

DBperl is the old name for the interface specification. Its usually now used to denote perl4 modules on database interfacing, such as, oraperl, isqlperl, ingperl and so on. These interfaces didnt have a standard API and are generally not supported.

Heres a list of DBperl modules, their corresponding DBI counterparts and support information. Please note, the authors listed here generally do not maintain the DBI module for the same database. These email addresses are unverified and should only be used for queries concerning the perl4 modules listed below. DBI driver queries should be directed to the dbi-users mailing list.

However, some DBI modules have DBperl emulation layers, so, DBD::Oracle comes with an Oraperl emulation layer, which allows you to run legacy oraperl scripts without modification. The emulation layer translates the oraperl API calls into DBI calls and executes them through the DBI switch.

Heres a table of emulation layer information:

Module Emulation Layer Status
------ --------------- ------
DBD::Oracle Oraperl Complete
DBD::Informix Isqlperl Under development
DBD::Ingres Ingperl Complete?
DBD::Sybase Sybperl Working? ( Needs verification )
DBD::mSQL Msqlperl Experimentally released with
DBD::mSQL-0.61

The Msqlperl emulation is a special case. Msqlperl is a perl5 driver for mSQL databases, but does not conform to the DBI Specification. Its use is being deprecated in favour of DBD::mSQL. Msqlperl may be downloaded from CPAN via:

http://www.perl.com/cgi-bin/cpan_mod?module=Msqlperl