Php 在页面刷新时填充数据库

我有一个脚本，可以验证数据并将其提交到MySQL数据库，但每当在新选项卡中刷新或重新访问索引页时，都会填充数据库。填充的数据为空。我想停止自动重新提交数据，但不确定如何进行

这是我的脚本，用于验证数据并将其提交到数据库

<?php include('includes/config.php');
    // define variables and set to empty values
$nameErr = $contactErr = $cityErr = $serviceErr = "";
$name = $contact = $city = $service = "";

function test_input($data) 
  {
   $data = trim($data);
   $data = stripslashes($data);
   $data = htmlspecialchars($data);
   return $data;
  }

if ($_SERVER["REQUEST_METHOD"] == "POST") {

   if (empty($_POST["name"])) {
     $nameErr = "* Name is required";
   } else {
     $name = test_input($_POST["name"]);
     // check if name only contains letters and whitespace
     if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
       $nameErr = "* Only letters and white space allowed";
     }
   }

   if (empty($_POST["contact"])) {
     $contactErr = "* Contact is required";
   } else {
     $contact = test_input($_POST["contact"]);
     // check if contact number is well-formed
     if (!preg_match("/^[0-9+]*$/",$contact)) {
       $contactErr = "* Phone number should contain only numbers";
     }
   }

   if (empty($_POST["city"])) {
     $cityErr = "* City is required";
   } else {
     $city = test_input($_POST["city"]);
     // check if city is valid
     if (!preg_match("/^[a-zA-Z ]*$/",$city)) {
       $cityErr = "* Only letters and white space allowed";
     }
   }

   if (empty($_POST["service"])) {
     $serviceErr = "* Service is required";
   } else {
     $service = test_input($_POST["service"]);
   }
 } 

    $myDb->connect();
    $query = "INSERT INTO user_profile (name, city, contact, service)VALUES('$name', '$city', '$contact', '$service')";
    mysql_query($query) or die(mysql_error());
    $myDb->close();
    $display_error = "Data submitted successfully."; 


?>

这是我的表格

 <form action="index.php"  method="post">

    <table style="line-height: 50px;">
        <tr>
          <th>Name&nbsp;&nbsp;&nbsp;</th>
          <td><input type="text" name="name" placeholder="Your Name" style="height:30px; border:1px; width:300px; border-radius:5px; text-indent:15px"><span class="error"> <?php echo $nameErr;?></span></td>
        </tr>
        <br>
        <tr>
          <th>Phone&nbsp;&nbsp;&nbsp;</th>
          <td><input type="text" name="contact" placeholder="Your Contact Number" style="height:30px; border:1px; width:300px; border-radius:5px; text-indent:15px"><span class="error"> <?php echo $contactErr;?></span></td>
        </tr>
        <tr>
          <th>City&nbsp;&nbsp;&nbsp;</th>
          <td><input type="text" name="city" placeholder="Your City Name" style="height:30px; border:1px; width:300px; border-radius:5px; text-indent:15px"><span class="error"> <?php echo $cityErr;?></span></td>
        </tr>
        <tr>
          <th>Service&nbsp;&nbsp;&nbsp;</th>
          <td><select name="service" autocomplete="off" style="height:30px; border:1px; width:300px; border-radius:5px;">
              <option value="">Select your service</option>
              <option value=service1>Service 1</option>
              <option value=service2>Service 2</option>
              <option value=service3>Service 3</option>
              <option value=service4>Service 4</option>
              </select><span class="error"> <?php echo $serviceErr;?></span></td>
        </tr>
    </table>
    <input type="submit" name="submit" value="Submit" style="height: 40px; width: 140px; border-radius: 5px; margin-left: 140px;margin-top: 20px;">
    </form>

我不知道我犯了什么错误。每次打开包含表单的index.php页面时，都会自动添加一个新的空白数据库。我怎样才能防止这种情况？请帮帮我。

$myDb->connect； $query=插入用户_配置文件名称、城市、联系人、服务值“$name”、“$city”、“$contact”、“$service”； mysql\u query$query或diemsql\u错误； $myDb->close； $display\u error=数据提交成功

这应该在if语句中

if ($_SERVER["REQUEST_METHOD"] == "POST") {

到

---

该语句应该位于if语句中，在该语句中检查请求是否为POST，并在执行该代码之前检查是否有任何错误。

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