如何使用插入ID插入另一个表？

I've got a problem like this , I cannot get the id of the parent table .

table_name : transaction_tbl

- transaction_id
-file_name
-file_path
-description

table_name : transaction_details
-details_id
-transaction_id
- details 

here is my code to insert :

$sql = "INSERT INTO transaction_tbl (`file_name`,`file_path`,`description`) VALUE('$file_name','$file_path','$description') " ;

$query = $conn->query($sql);
$transaction_id = mysqli_insert_id($conn);
if ($query === True ){
      $sql = "INSERT INTO transaction_details (`transaction_id`,`details`) VALUES ($transaction_id,$details) ";
}else {
      trigger_error('Wrong SQL: ' . $sql . 'Error: ' . $conn->error, E_USER_ERROR);
}

Now I can insert in my transaction_tbl but not in transaction_details. what should I do? Can somebody help me?

Add $query = $conn->query($sql); inside if condition as below

if ($query === True ){
      $sql = "INSERT INTO transaction_details (`transaction_id`,`details`) VALUES ($transaction_id,$details) ";
      $query = $conn->query($sql);
}
else {
          trigger_error('Wrong SQL: ' . $sql . 'Error: ' . $conn->error, E_USER_ERROR);
}