Html 如何向文本框显示数据库值

//PHP代码

<?php
    $conn=mysqli_connect("localhost", "root", "", "dlt");
    if(!$conn){
    die("Connection Failed: " . mysqli_connect_error());
  } 

  if(isset($_POST["searchbutton"])){
  $sql="SELECT * FROM professional where LicenceNumber LIKE '".@$_POST['searchbox']."' ";
  $result=mysqli_query($conn, $sql);

  if(mysqli_num_rows($result) > 0){
  while($row=mysqli_fetch_array($result)){

    $licenseno=$row['LicenceNumber']; 
    $fname=$row["FirstName"]; 
    $mname=$row["MiddleName"]; 
    $lname=$row["LastName"];
    $adres=$row["Address"];
    $bdate=$row["BirthDate"]; 
    $sex=$row["Sex"]; 
    $height=$row["Height"]; 
    $weight=$row["Weight"];
    $nationality=$row["Nationality"]; 
    $issue=$row["DateIssued"]; 
    $expiration=$row["ExpirationDate"];  


  } 
} else {
    echo "No Record Found";
}
}
  mysqli_close($conn);
?>

//搜索框和搜索按钮

<form action="manage_professional.php" method = "post">
<div class="w3-padding-32">
<div class="w3-bar w3-card-2 w3-small">
<form action = "manage_professional.php" method = "post">
     <input class="w3-input w3-border w3-bar-item " type="text" placeholder="Licence No." name="searchbox" maxlength="11" size="65" required> 
     <button name="searchbutton" type="submit" class="w3-bar-item w3-white 
   w3-button w3-border">SEARCH</button>
    </form>
    </div>
    </div>



    // TEXTBOXES // 3 columns 


  <form action = "manage_professional.php" method = "get">
  <div class="w3-third w3-margin-bottom">
  <div class="w3-container w3-white">
    <p><input  value='<?php echo $licenseno?>' name="licenseno" id="licenseno" class="w3-input w3-border" type="text" placeholder="License number" required></p>
    <p><input  class="w3-input w3-border" type="text" placeholder="First name" required></p>
   <p><input  class="w3-input w3-border" type="text" placeholder="Middle name"   required></p>
   <p><input  class="w3-input w3-border" type="text" placeholder="Last name"   required></p>
  </div>
</div>

<div class="w3-third w3-margin-bottom">
  <div class="w3-container w3-white"><p><input class="w3-input w3-border" type="text" placeholder="Address" name="address" required></p>
  <p><input class="w3-input w3-border" type="text" placeholder="Birthdate" name="bdate" onfocus="(this.type='date')" onblur="(this.type='text')" required></p>
  <p><input class="w3-input w3-border" type="text" placeholder="sex" name="sex" required></p>
  <p><input class="w3-input w3-border" type="text" placeholder="Height" name="height" required></p>
  </div>
</div>

<div class="w3-third w3-margin-bottom">
  <div class="w3-container w3-white">
    <p><input class="w3-input w3-border" type="text" placeholder="Weight" name="weight" required></p>
    <p><input class="w3-input w3-border" type="text" placeholder="Nationality" name="nationality" required></p>
    <p><input class="w3-input w3-border" type="text" placeholder="Date issued" name="issue"  onfocus="(this.type='date')" onblur="(this.type='text')" required></p>
    <p><input class="w3-input w3-border" type="text" placeholder="Expiration date" name="expiration" onfocus="(this.type='date')" onblur="(this.type='text')" required></p>
  </div>
</div>

<button type="submit" class="w3-button w3-black w3-margin-bottom w3-round" name = "addbutton" style="width:20%">EDIT</button>
<button type="submit" class="w3-button w3-black w3-margin-bottom w3-round" name = "delbutton" style="width:20%">DELETE</button>
</form>
</div>
</form>

搜寻
//文本框//3列
默认情况下，当表单第一次加载时，它不会进入if（isset（$\u POST[“searchbutton”]）条件，$licenseno将显示未定义的错误，否则if（isset（$\u POST[“searchbutton”]）将$licenseno设置为null以避免此错误
建议
您不仅应该选中searchbutton，还应该选中searchbox by
isset
哪一行是152？编辑您的问题并在行中添加注释，如
//Error line#152
，licenseno来自该行