php – 我的AJAX查询没有正确验证

这里是网页设计的新手.我有一个登录表单,验证并在php中完美运行但是当我尝试使用ajax进行验证时它不起作用.当我运行页面时,它表示无论输入到表单中它都是成功的.我已经尝试了几天试图让它在许多不同的方法中进行验证.如果有更好的方法请告诉我！

这里的PHP和登录表单在同一页面上

if (isset($_POST['login'])) {

    $email = mysqli_real_escape_string($con,$_POST['email']);
    $password = mysqli_real_escape_string($con,$_POST['password']);
    $result = mysqli_query($con,"SELECT * FROM users WHERE email = '" . $email. "' and password = '" . md5($password) . "'");

    if ($row = mysqli_fetch_array($result)) {
        echo json_encode('true');
        $_SESSION['usr_id'] = $row['id'];
        $_SESSION['usr_name'] = $row['name'];
        $_SESSION['logged_in'] = true;


    } else {
        echo json_encode('false');
        $errormsg = "Incorrect Email or Password!!!";
    }
}


?>

$(document).ready(function() {
  $('#login_submit').click(function() {
      var form = $('#login_form').serialize();
    $.ajax({
        type: "POST",url: "header.php",data: form,success:function (response){
                
                alert('Hi');
        
        },error: function(response){
                
                alert('Nope');
            
        }
          
        
   });
 });
});

<form id="login_form" form role="form" action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post" name="loginform">
                
                <label class="login_form_labels"> Email:</label>
                
                <input type="email" id="email" class="login_input" name="email"><br><br>
                
                <label class="login_form_labels"> Password:</label>
                
                <input type="password" id="password" class="login_input" name="password"><br>
                
                <div id="stay_log">
                    Stay logged in.
                    
                    <input type="checkbox" name="stayLoggedIn" value=1 id="checkbox_1">
                    
                </div>
                
                
                <input class="login_form_btn" name="login" value="Submit" type="Submit" id="login_submit">
                
                <button class="login_form_btn" type="button">Forget your Password?</button>

            </form>

请帮忙！

$.ajax({
    type: "POST",dataType: json,success:function (response){
            alert('Hi');
    },error: function(response){
            alert('Nope');
    }
});