Programming the Perl DBI

Disconnection

Explicit disconnection from the database is not strictly necessary if you are exiting from your program after you have performed all the work, but it is a good idea. We strongly recommend that you get into the habit of disconnecting explicitly.

DBI provides a method through which programmers may disconnect a given database handle from its database. This is good practice, especially in programs in which you have performed multiple connections or will be carrying out multiple sequential connections.

The method for performing disconnections is:

$rc = $dbh->disconnect();

According to this definition, disconnect() is invoked against a specific database handle. This preserves the notion that database handles are completely discrete. With multiple database handles active at any given time, each one must explictly be disconnected.

An example of using disconnect() might look like:

#!/usr/bin/perl -w
#
# ch04/disconnect/ex1: Connects to an Oracle database
#                      with auto-error-reporting disabled
#                      then performs an explicit disconnection.

use DBI;            # Load the DBI module

### Perform the connection using the Oracle driver
my $dbh = DBI->connect( "dbi:Oracle:archaeo", "username", "password" , {
            PrintError => 0
        } )
    or die "Can't connect to Oracle database: $DBI::errstr\n";

### Now, disconnect from the database
$dbh->disconnect
    or warn "Disconnection failed: $DBI::errstr\n";

exit;

Upon successful disconnection, the return value will be true. Otherwise, it will be false. In practice, failure ...