问题
I need to calculate the time a user spends on site. It is difference between logout time and login time to give me something like "Mr X spent 4 hours and 43 minutes online". So to store the4 hours and 43 minutes i declared it like this:
duration time NOT NULL
Is this valid or a better way to store this? I need to store in the DB because I have other calculations I need to use this for + other use cases.
回答1:
Storing it as an integer number of seconds will be the best way to go.
- The
UPDATEwill be clean and simple - i.e.duration = duration + $increment - As Tristram noted, there are limitations to using the
TIMEfield - e.g. "TIMEvalues may range from'-838:59:59'to'838:59:59'" - The days/hours/minutes/seconds display formatting won't be hardcoded.
- The execution of your other calculations will almost surely be clearer when working with an integer "number of seconds" field.
回答2:
I wouldn't use time as you would be limited to 24 hours. The easiest would just to store an integer in minutes (or seconds depending on the resolution you need).
回答3:
Consider storing both values as a UNIX-epoch-delta.
I generally prefer to use a signed (64b) bigint (for secondly resolution), or a (signed) (64b) double (if fractional seconds are needed), or a signed (32b) int (if scaled down to minutely or hourly).
Make the unit explicit in the name of the column, for example with a suffix like "_epoch_minutely", for example: "started_epoch_minutely", "finished_epoch_minutely".
来源：https://stackoverflow.com/questions/4498513/mysql-storing-duration-time-datatype