从一个数据库中选择并使用匹配的行更新到另一个

Question

select a database values and update into another database with same id : where the error i getting is Trying to get property of non-object how can i achieve it is there any solution ??

   $servername = "localhost";
   $username = "root";
   $password = "pass";
   $dbname = "db1";
   $dbname2="db2";


   $conn = new mysqli($servername, $username, $password, $dbname);

   if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
   } 


   $conn2 = new mysqli($servername, $username, $password, $dbname2);

   if ($conn2->connect_error) {
die("Connection failed: " . $conn2->connect_error);
   } 

   $sql = "SELECT * FROM affiliates";
   $result = $conn->query($sql);

   if ($result->num_rows > 0) {
   //output data of each row

      while($row = $result->fetch_assoc()) {
            echo "from db1 id: " . $row["id"]. "publish " .$row["publishinsuppliercontants"]. "<br>";

      $sql2 = "UPDATE a1_affilates_cstm SET publish_in_supplier_contacts_c=".$row["publishinsuppliercontants"]." WHERE id_c=".$row["id"]."";
     $result2 = $conn2->query($sql2);

    $sql2 = "SELECT * FROM a1_affilates_cstm WHERE id_c = ". $row["id"]."";

    $result2=mysqli_query($conn2,$sql2) or die mysqli_error($conn2);
    $row1 = mysqli_fetch_array($result2);
   ///check whether inserted ...
           echo "from db2 id: " . $row1["id_c"]. " - publish: ".row1["publish_in_supplier_contacts_c"]. " <br>";

       }
   } else {
       echo "0 results";
   }

Answer 1

It looks like you don't get the result object. Is the SELECT query was successfully ?

You need to check the select query state/result before make operation with result object.

For example in your case:

$sql = "SELECT * FROM affiliates";
if ( $result = $conn->query($sql) ) {
  if ($result->num_rows > 0) {
     ... some logic ...

From PHP mysqli manual:

"Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or EXPLAIN queries mysqli_query() will return a mysqli_result object. For other successful queries mysqli_query() will return TRUE."