Programming the Perl DBI

Naming Conventions and Name Space

The DBI package and all packages below it (DBI::*) are reserved for use by the DBI. Extensions and related modules use the DBIx:: namespace (see http://www.perl.com/CPAN/modules/by-module/DBIx/). Package names beginning with DBD:: are reserved for use by DBI database drivers. All environment variables used by the DBI or by individual DBDs begin with DBI_ or DBD_.

The letter case used for attribute names is significant and plays an important part in the portability of DBI scripts. The case of the attribute name is used to signify who defined the meaning of that name and its values, as the following table shows.

Case of Name	Has a Meaning Defined By
UPPER_CASE	Standards, e.g., X/Open, ISO SQL92, etc. (portable)
MixedCase	DBI API (portable), underscores are not used
lower_case	Driver or database engine specific (non-portable)

It is of the utmost importance that driver developers use only lowercase attribute names when defining private attributes. Private attribute names must be prefixed with the driver name or suitable abbreviation (e.g., ora_ for Oracle, ing_ for Ingres, etc.).

Here’s a sample of the Driver Specific Prefix Registry:

ado_     DBD::ADO
best_    DBD::BestWins
csv_     DBD::CSV
db2_     DBD::DB2
f_       DBD::File
file_    DBD::TextFile
ib_      DBD::InterBase
ing_     DBD::Ingres
ix_      DBD::Informix
msql_    DBD::mSQL
mysql_   DBD::mysql
odbc_    DBD::ODBC
ora_     DBD::Oracle
proxy_   DBD::Proxy
solid_   DBD::Solid
syb_     DBD::Sybase
tuber_   DBD::Tuber
xbase_   DBD::XBase