Database Reference
In-Depth Information
DBI connect Syntax
The DBI call for establishing a database session is
connect
. It has the following syntax:
$dbh = DBI->connect($data_source, $username, $auth, \%attr);
In Perl, names of scalar variables are prefixed by
$
, and hashes by
%
(please run
perldoc
perlintro
for an explanation of the terms scalar and hash). Table 22-3 explains the parameters
of the
connect
call.
Table 22-3.
connect Parameters
Parameter
Meaning
$dbh
Database handle for the database session.
$data_source
Data source, i.e., specification for connecting to a local ORACLE instance
or contacting a listener. The following formats are supported:
"DBI:Oracle:"
,
"DBI:Oracle:<Net service name>"
,
"DBI:Oracle:host=<host_name>;port=<port_number>;sid=<ORACLE_SID>"
,
"DBI:Oracle:<host_name>:<port_number>/<instance_service_name>"
,
5
or
undef
.
$username
Database username, “/” for OS authentication, or
undef
.
$auth
Password or
undef
.
\%attr
Optional reference to a hash with connect options.
The Perl keyword
undef
represents an undefined value analogous to
NULL
in SQL. If one of
$data_source
,
$username
, or
$auth
are
undef
, then environment variables are used, if available.
Table 22-4 lists the parameters and the corresponding environment variables.
5
Table 22-4.
Perl DBI Environment Variables
Parameter
Environment Variable
$data_source
DBI_DSN
$username
DBI_USER
$auth
DBI_PASS
The value of
$data_source
must always start with the string “DBI:Oracle:”. Note that the
uppercase “O” in the string “Oracle” as well as the colon (:) after the string “Oracle” are manda-
tory. Using a lowercase “o” causes the following error:
DBD::oracle initialisation failed: Can't locate object method "driver" via package
"DBD::oracle"
5. The Oracle Net easy connect format is available in Oracle10g and subsequent releases.
