尝试使用文本框PHP中的输入值更新数据库

what i am trying to do is to get the value inputed in the textbox then insert that value into the database

this code seems to be working but it only changes the value chosen to 0

   <?php

 $q1 = $_POST['q1'] ;
$q2 = $_POST['q2'] ;
$q3 = $_POST['q3'] ;
$q4 = $_POST['q4'] ;

$qe = $_POST['qe'] ;

$LT1 = $_POST['LT1'] ;
$LT2 = $_POST['LT2'] ; 

$THW = $_POST['THW'] ;
$TSW = $_POST['TSW'] ;

$Ct = $_POST['Ct'] ;
$Pj = $_POST['Pj'] ;

$insert = mysql_query("UPDATE grades SET HQ1 = ' . $q1 . ' WHERE ID='4011909'");

?>

remove the concatenation symbol in the query

$insert = mysql_query("UPDATE grades SET HQ1 = '$q1' WHERE ID='4011909'");