问题
Mysqli prepared statements like the one below throw the following error when get_result() is called.
$stmt = $connection -> prepare("select column from table where id = ?");
$stmt -> bind_param("i", $id);
$id = 1;
$stmt -> execute() or trigger_error($stmt -> execute(), E_USER_ERROR);
$stmt_result = $stmt -> get_result();
$stmt_numrows = $stmt_result -> num_rows;
$stmt -> close();
Fatal error: Uncaught Error: Call to undefined method mysqli_stmt::get_result()
After reading the contribution section of the manual, it looks like it's a module issue. The doc here http://php.net/manual/en/mysqli-stmt.get-result.php states "Available only with mysqlnd", which is already enabled on the server.
It seems that everything works when I disable the mysqli extension and enable nd_mysqli instead (also recommended here: get_result() Doesn't Work even mysqlnd is enabled but with no further explanation).
I'd like to know what else I commit to by swapping these two extensions since they conflict with one another and can't be enabled together. Am I going to lose some features in the process? What's the difference between these two extensions exactly besides nd_mysqli including get_result()?
来源：https://stackoverflow.com/questions/53871567/difference-between-php-extensions-mysqli-and-nd-mysqli