locking database table example

                $i=0;
                do {
                    $result = $this->mysqli->query("SELECT * FROM `lock` WHERE `table_name`='USER'");
                    $numRows = $result->num_rows;
                    if ($numRows > 0) {
                        echo "Waiting for table (USER) count: " . $i + 1 ;
                        sleep(0.05);
                        $i++;
                    }
                } while ($numRows > 0 && $i < 9);
                if ($i == 9) {
                    echo "Previous lock (USER) timeout";
                    $this->mysqli->query("DELETE `lock` WHERE `table_name`='USER' ");
                    echo "Previous lock destroyed (USER)";
                }
                $this->mysqli->query("INSERT INTO `lock`(`table_name`) VALUES ('USER')");
                echo "Lock taken (USER)";
                $stmt_user->bind_param("ssssss", $this->name, $this->contactNumber, $this->email, $this->password, $this->salt, $this->gender) or trigger_error(mysql_error());
                $stmt_get_user_id->bind_result($USER_id) or trigger_error(mysql_error());
                $stmt_user->execute() or trigger_error(mysql_error());
                $stmt_get_user_id->execute() or trigger_error(mysql_error());
                $stmt_get_user_id->store_result() or trigger_error(mysql_error());
                $stmt_get_user_id->fetch() or trigger_error(mysql_error());
                $this->mysqli->query("DELETE `lock` WHERE `table_name`='USER' ");
                echo "Lock given up (USER)";