The RaiseError attribute can be used to force errors to raise exceptions rather than simply return error codes in the normal way.

##</code><code>##

#!/usr/bin/perl
use DBI;
use v5.10;
use strict;
use warnings;
use feature 'say';
use Config::Simple;

my %config = ();
my $path = 'conf.ini';

sub mysql_con {
    Config::Simple->import_from("".$path."", \%config)
	or die Config::Simple->error();

    my $dbh = DBI->connect("dbi:mysql::".$config{'MySQL.host'}.":".$config{'MySQL.port'}."", 
			   "".$config{'MySQL.user'}."",
			   "".$config{'MySQL.pass'}."",
			   { 'PrintError' => 1, 'RaiseError' => 1 , 'AutoInactiveDestroy' => 1 }
	) or die "Could not connect to ". $config{'MySQL.host'} .": ". $DBI::errstr ."\n";

    my $databases = $dbh->do("SHOW DATABASES LIKE '".$config{'MySQL.db'}."'")
	or die "Error: " .dbh->errstr. "\n";

    $dbh->disconnect()
	or warn "Error disconnecting: $DBI::errstr\n";

    if ($databases eq 1) {
	return "Database: ". $config{'MySQL.db'} .
	    " exists not creating: ". $config{'MySQL.db'} ."";
    }
    return "Database: ". $config{'MySQL.db'} .
	" does not exist create: ". $config{'MySQL.db'} ."";
}

say mysql_con();

##</code><code>##

[MySQL]
user=user
pass=password
host=localhost
port=3306
db=PerlMonks

##</code><code>##

#!/usr/bin/perl
use DBI;
use v5.10;
use strict;
use warnings;
use feature 'say';
use Config::Simple;

my %config = ();
my $path = 'conf.ini';

sub mysql_con {
    Config::Simple->import_from("".$path."", \%config)
	or die Config::Simple->error();

    my $dbh = DBI->connect("dbi:mysql::".$config{'MySQL.host'}.":".$config{'MySQL.port'}.",
			   mysql_ssl=1;
			   mysql_ssl_client_key=/etc/mysql/certs/client-key.pem; 
			   mysql_ssl_client_cert=/etc/mysql/certs/client-cert.pem;
			   mysql_ssl_ca_file=/etc/mysql/certs/ca-cert.pem",
			   $config{'MySQL.user'},
			   $config{'MySQL.pass'},
			   { 'PrintError' => 1, 'RaiseError' => 1 , 'AutoInactiveDestroy' => 1 }
	) or die "Could not connect to ". $config{'MySQL.host'} .": ". $DBI::errstr ."\n";

    my $databases = $dbh->do("SHOW DATABASES LIKE '".$config{'MySQL.db'}."'")
	or die "Error: " .dbh->errstr. "\n";

    $dbh->disconnect()
	or warn "Error disconnecting: $DBI::errstr\n";

    if ($databases eq 1) {
	return "Database: ". $config{'MySQL.db'} .
	    " exists not creating: ". $config{'MySQL.db'} ."";
    }
    return "Database: ". $config{'MySQL.db'} .
	" does not exist create: ". $config{'MySQL.db'} ."";
}

say mysql_con();

__END__

$ perl mysql.pl
Database: PerlMonks exists not creating: PerlMonks