Transaction

try
  {
   $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password, array(PDO::ATTR_PERSISTENT => true));
  }
  catch(PDOException $e)
  {
   echo $conn . "<br>" . $e->getMessage();
   exit();
  }

try
  {
   // set the PDO error mode to exception
   $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

   // start transaction
   $conn->beginTransaction();
   $conn->query("SET NAMES 'utf8'");
   $q="SELECT * FROM synagogue.customer_table WHERE first_name='$first_name' AND last_name='$last_name'";
   $query_res = $conn->query($q);
   $count= count($query_res->fetchAll());
   if($count > 0)
   {
    echo "מתפלל קיים";
   }

   else
   {
    $table_customer = "customer_table";
    $table_debts = "debts_balance";

    $data_customer = array
    (
     "first_name" => "$first_name",
     "last_name" => "$last_name",
     "address" => "$address",
     "tel" => "$tel",
     "mail" => "$mail"
    );
    $sql = "INSERT INTO `$table_customer` (`".implode('`,`',array_keys($data_customer))."`) VALUES ('".implode('\',\'',array_values($data_customer))."');";

    $conn->exec($sql);

// read the last ID
    $last_id = $conn->lastInsertId();
    $date = date('Y-m-d');
    $sql = "INSERT INTO `synagogue`.`debts_balance` (customer_id, date, debt_balance) VALUES ('$last_id', '$date', 0)";
    $conn->exec($sql);

    $conn->commit();
    echo "ברוך הבא למתפלל החדש";
   }
  }
  catch(PDOException $e)
  {
   $conn->rollBack();
   echo $sql . "<br>" . $e->getMessage();
  }
  $conn = null;

 ?>