PHP-每个组显示一次类别

类别，同时仅显示一次类别标题。我有一个表保存类别标题（父级），第二个表保存子类别信息。虽然在显示信息时，我不知道如何只显示一次类别信息

$result_array = mysqli_query($connect, "SELECT * 
                                        FROM tbl_customer, categories 
                                        WHERE tbl_customer.category_QA = categories.id 
                                        ORDER BY Category ASC");

while ($data = mysqli_fetch_array($result_array)) {
    echo $data["Category"];    //display once for every new category
    echo $data["productName"];
}

---

你可以找零钱

$result_array = mysqli_query($connect,"SELECT * FROM tbl_customer, categories WHERE tbl_customer.category_QA = categories.id ORDER BY Category ASC");

$checkCategory = '';
while($data = mysqli_fetch_array($result_array)){

   if  ($checkCategory != $data["Category"]){
      echo $data["Category"]; //display once for every new category
      $checkCategory = $data["Category"];
  }
  echo $data["productName"];
}

---

你可以找零钱

$result_array = mysqli_query($connect,"SELECT * FROM tbl_customer, categories WHERE tbl_customer.category_QA = categories.id ORDER BY Category ASC");

$checkCategory = '';
while($data = mysqli_fetch_array($result_array)){

   if  ($checkCategory != $data["Category"]){
      echo $data["Category"]; //display once for every new category
      $checkCategory = $data["Category"];
  }
  echo $data["productName"];
}

---

@奇雷尔。。谢谢答案已更新。。在你是宝石的地方投票@奇雷尔。。谢谢答案已更新。。在你是宝石的地方投票。