mysql，如何将四舍五入的数字保存到longtext字段中？

Question

I have done this calculation:

$number = round(count($exc)/ count($grades),2,PHP_ROUND_HALF_UP);

When save,I have to save it into a field of an existing table which is a longtext type. The numbers got saved but become very long, something like 0.200000000000000011102230246251565404236316680908203125 I think this might cause extra db storage. When I query the numbers, they are still rounded as 2 digital. So, that's an extra converting job. I would like to learn how to save those numbers as rounded number?

Answer 1

You can use PHP sprintf function coupled with format specifier like so:

$number = sprintf("%.3f", round(count($exc)/ count($grades),2,PHP_ROUND_HALF_UP));

If you need more info about that take a look at sprintf PHP documentation here http://it2.php.net/manual/en/function.sprintf.php .