#!/usr/bin/perl -w

use strict;
use DBI;
#db connect
my $driver = 'mysql';
my $database = 'usersdb';
my $dsn = "DBI:$driver:database=$database";
my $dbh = DBI->connect($dsn, undef, undef);
my $user ="bob";
my $user_test = user_exists($user);
if (defined $user_test){
	print "user $user is already in our database";
}else{
	#code to insert user
}

$dbh->disconnect;

sub user_exists{
	my $id_val = shift;
	my $statement = "select user_id from users where user_id = $id_val";
	my $ary_ref = $dbh->selectall_arrayref($statement);
	if (defined $ary_ref->[0]->[0]){
		return $ary_ref->[0]->[0];
	}else{
		return undef;
	}
	
}