防止重复表单输入

Question

我需要防止表单数据的重复数据输入。 功能是：表单包含部分和学生数量。我们可以添加多个部分。我需要防止重复的部分名称。 请查看代码，

$connect = mysqli_connect("localhost","root","mysql","inventory");
$number = count($_REQUEST["name"]);

if($number > 0)
{
    for($i=0; $i<$number; $i++)
    {
        if(trim($_REQUEST["name"][$i]) != '')
        {

            $id = $_REQUEST['idref'];
            $c = $_REQUEST["clas"];
            $s = $_REQUEST["name"][$i];
            $k = $_REQUEST["k"][$i];
            $query = mysqli_query($connect, "SELECT * FROM budget WHERE section='".$s."'");
                if(mysqli_num_rows($query) > 0)
                    {
                        echo "already exists";
                    }
                else
                    {
                        $sql = "INSERT INTO budget(sid,k,section,stu) VALUES('$id','$c','$k','$s')";
                        mysqli_query($connect, $sql);
                    }
        }
    }   
}
else
{echo "Enter section";

}