How to avoid submitting twice?

hello all, I am having a form which contains a dropdown listbox and a submit button. The user will choose any number from 1 to 5 and hits the submit button. After this the data that he had selected (1,2,3,4 or 5) enters into a mysql database(this data enters into the row with the latest userid) and a link appears, so that by click that link he can go to next page. I want to avoid the user from submitting his opinion once again if he does it already. Here is the code that i have wrote, which is going logically some where wrong. FYI : opinion and submit are the names of the dropdown listbox and submit buttons. scene1 is the name of the field in the table named testtable into which the data enters(one of 1 to 5) mysql_connect ('localhost','myname','password') or die ('<b>unable to connect to the database.</b>'); mysql_select_db ('usertest') or die ('<b>unable to select the database.</b>'); if ($submit) { $result = mysql_query("select * from testtable order by userid desc limit 1"); $myrow = mysql_fetch_array ($result); $id = $myrow["userid"]; $query = "update testtable set scene1='$opinion' where userid=$id"; mysql_query ($query); echo "<a href=next.php>Go to next page</a>"; /* this is the part i am trying to use to avoid him from doing submission second time */ $result=mysql_query("select * from testtable order by userid desc limit 1"); $myrow = mysql_fetch_array ($result); $scene1 = $myrow["scene1"]; if ($scene1 == 1||2||3||4||5) { echo "<script language=\"javascript\">"; echo "alert(\"You can choose the rating only once\");"; echo "</script>"; } } Thanks Chakravarthy K Sannedhi __________________________________________________ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/