Don't write / duplicate email if it already exists

[eddiethebutler]

I have used some software (Forms To Go) to make a PHP script that writes to a mySQL database (I am collecting names and emails for newsletters).

I have customised it so that it only writes to the database if the Y box is checked and now I want it to only add the email address if it isn't already present BUT I still want the user to be redirected to a confirmation page AND for me to get an email confirming their name & email.

I have added a piece of script to try and check for existing email address using in_array but I really don't know what i am doing so any help would be appreciated.

Here is the script

if ( $FTGnewsletter == "newsletterY" ) {
 
// the above is the part that only runs the following if Y box is checked
 
// below is all by FTG apart from the email check code
 
#====================================================
# Dump field values to a MySQL table                =
#====================================================
 
 
 
$mysql_link = @mysql_connect("mysql2.address.com", "username", "password");
 
if (mysql_errno() > 0) {
   echo 'MySQL error # ' . mysql_errno() . ' : ' . mysql_error() . '<br>';
   exit;
}
 
if (mysql_errno() == 0) {
 
 @mysql_select_db("database_name", $mysql_link);
 
 if (mysql_errno() > 0) {
    echo 'MySQL error # ' . mysql_errno() . ' : ' . mysql_error() . '<br>';
    exit;
 }
 
}
 
// i have added email check code here
 
if (!in_array ($FTG_sendersemail, $FTG_sendersemail)) {
$FTG_sendersemail[] =$FTG_sendersemail;
 
# Redirect user to success page
 
header("Location: confirmation.htm");
 
}
 
else   
 
// this is the end of the email check code
 
if (get_magic_quotes_gpc()) {
 $FTG__sendersname = stripslashes($FTG_sendersname);
 $FTG__sendersemail = stripslashes($FTG_sendersemail);
} else {
 $FTG__sendersname = $FTG_sendersname;
 $FTG__sendersemail = $FTG_sendersemail;
}
 
if (mysql_errno() == 0) {
 
 $sqlcmd = sprintf("INSERT INTO `nws_ltter`(`_sendersname`, `_sendersemail`) VALUES('%s', '%s')",
                   mysql_real_escape_string($FTG__sendersname, $mysql_link),
                   mysql_real_escape_string($FTG__sendersemail, $mysql_link));
 
 @mysql_query($sqlcmd, $mysql_link);
 
 if (mysql_errno() > 0) {
    echo 'MySQL error # ' . mysql_errno() . ' : ' . mysql_error() . '<br>';
    exit;
 }
 
}
 
} // this is the end of the newsletterY code 

[hawkenterprises]

Why not just search for a contact or newsletter script? It's much easier to drive your car to work instead of trying to build a new car.