插入查询不起作用，如果和否则两个循环都在执行

我正在尝试根据某些条件将数据插入新表中。我正在从现有表中获取此数据，然后将其存储在变量中。使用这些变量，我将其插入新表中。数据存储在变量中，但插入查询不起作用。还有 if 和 else 循环，两者都被执行。 -->

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) 
{
    die("Connection failed: " . $conn->connect_error);
} 
$sql = "SELECT * FROM creg";
$result = $conn->query($sql);
if ($result->num_rows > 0) 
{
    // output data of each row
    while($row = $result->fetch_assoc()) 
    {
        echo "id: " . $row["id"]. " - Name: " . $row["c_fname"]. " " . $row["post"]. " " . $row["c_qualification"]. $row["c_moname"]. " ". $row["c_WorkEx"]. "<br>";
        $id=$row['id'];
        $timestamp=$row['timestamp'];
        $post=$row["post"];
        $qual=$row["c_qualification"];
        $c_fname=$row['c_fname'];
        $c_lname=$row['c_lname'];
        $c_mname=$row['c_mname'];
        $c_moname=$row['c_moname'];
        $c_gender=$row['c_gender'];
        $c_email=$row['c_email'];
        $c_DOB=$row['c_DOB'];
        $c_contact=$row['c_contact'];
        $c_address=$row['c_address'];
        $c_workex=$row['c_WorkEx'];
        $servername = "localhost";
        if($qual=="B.E." && $post=="Diploma teacher")
        {
              echo "The trial echo";echo "<br>";
              echo $c_workex ,$c_fname, $c_lname;
              mysql_query("INSERT INTO eligible (id ,c_fname, c_lname, c_mname, c_moname, c_gender, c_email, c_DOB, c_contact, c_address, c_qualification, c_workex, c_post)
                    VALUES ('$id','$timestamp','$c_fname','$c_lname','$c_mname','$c_moname','$c_gender','$c_email','$c_DOB','$c_contact','$c_address','$qual','$c_workex','$post')");
        }
        else 
        {
              echo "Error";
        }
    }
} 
else 
{
    echo "0 results";
}

$conn->close();
?>