Thank you I will read up and look into both of those.
-------EDIT----------
So having looked into both of those. 
Im still stuck. 
The download links for DBD-MYSQL are not working I found a copy of DBD-mysql.4.0.32 but cannot seem to get it to install correctly. 
If i try to install DBI using PPM install DBI it says no packages missing So it seems I have that installed.
But the code still returns #questerrors with a number of squares as the subject.
I do also have the mysql plugin and the DB is configured correctly there.
What im currently working with...
	Code:
	sub EVENT_SAY 
{ 
	my $wares = quest::saylink("wares", 1);
	if($text=~/Hail/i)
	{
		plugin::Whisper("Would you like me to reset my $wares ?") ;
	}
	if($text=~/wares/i)
	{
	plugin::Whisper("Restocking now!") ;
	$connect = plugin::LoadMysql();
	$query = "Delete from Merchantlist_temp where npcid =999260;";
        $query_handle->execute;
	plugin::Whisper("Restock complete!") ;
	}
	    quest::debug("$DBI::errstr") if $DBI::errstr;
}
 For this type of code would DBD-mysql be required or is DBI enough?
Or am I doing something foolish incorrectly?