问WordPress和PHP |检查数据库中是否存在行，如果存在，则不插入数据

EN

if(isset($_POST['contact_us'])) {
    $invalidContact = "<h5 class='invalidBooking'> Nope try again</h5>";
    $successContact = "<h5 class='invalidBooking'> Message Sent!</h5>";
    $table_name='contact_table';
    global $wpdb;

    $contact_name = esc_attr($_POST['contact_name']);
    $contact_email = sanitize_email($_POST['contact_email']);
    $subject = esc_attr($_POST['subject']);
    $message = esc_attr($_POST['message']);

    $error= array();


    if (empty($contact_name)) {
        $error['name_invalid']= "Name required";
    }
    if (empty($contact_email)){
        $error['email_invaild']= "Email required";
    }

    // Im guessing some code here to check if row exists in database

    if (count($error) >= 1) {
        echo $invalid;
    }
    if (count($error) == 0) {
        $data_array=array(
            'Contact_Name'=>$contact_name,
            'Contact_Email'=> $contact_email,
            'Contact_Subject'=> $subject,
            'Contact_Message'=> $message,
        );

        $rowResult=$wpdb->insert($table_name, $data_array,$format=NULL);
        echo $successContact;
    } 

}