* [EMAIL PROTECTED] > Hello, > I have a table bill like > when (date), how_much (float), what (varchar). > > Now I store some bills on it - how_much will get numbers with 2 digits > after point.
Why do you think that? Note that FLOAT is an approximate numeric type. The value you insert is stored in a binary format, and when you retrieve it, it may have a slightly different value from what you inserted, like you have observed. Read more here: <URL: http://www.mysql.com/doc/en/Problems_with_float.html > <URL: http://www.mysql.com/doc/en/Numeric_types.html > > Then I want to know how much money I spent each month. > SELECT SUM(how_much), YEAR(when), MONTH(when) FROM bill GROUP BY > (YEAR(when)*12+MONTH(when)) I don't understand this GROUP BY clause... the subject of this message indicates that this too was an issue? I would have expected "GROUP BY YEAR(when), MONTH(when)". > I expect to get numbers with not more than 2 digits after the point. > Surprisingly I get ??.259999978 when I expect to get ??.26 or some else > strange numbers. See the ROUND() function: <URL: http://www.mysql.com/doc/en/Mathematical_functions.html#IDX1291 > Note the C library dependency of this function, it may behave differently on different computers. I would store the how_much as pfennnigs or cents or whatever and use an INTEGER type. -- Roger -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
