Question

I have a situation where I want users to be able to specify a time range, where the time is a relative range that exist in a given week. So a user could pick Monday 5PM – Tuesday 1AM. Think of it kind of like “what time is a person’s work shift”.

My first reaction is that I could store “relative” times. So assuming the week starts on Monday at 00:00:00, Monday at noon would be indicated as 86400/2=43200. I don’t really like this method, because it makes handling time-zones a bit difficult.

Is there a “best” way for doing this (or just a good one)? Does MySQL have some sort of data type that deals with this specifically?

I’ve tagged this “Perl” and “MySQL”, since I will be using them for this application, but the answer doesn’t have to be specific to either of them technically.

Answer 1

The best answer will depend somewhat on what you will do with the data downstream.

But I would recommend avoiding any hacks and doing a straightforward approach (table syntax Sybase, since my MySQL is rusty – sorry)

CREATE TABLE weekday_ranges (
    start_dow    int,  -- 0-6 or 1-7 depending on what's easier downstream 
    start_hour   int,  -- 0-23
    start_minute int,  -- 0-59
    -- Add seconds/micorseconds as needed
    end_dow      int,
    end_hour     int,
    end_minute   int
)

An alternate approach is to store the offset ( in seconds ) from Sunday 00:00, both start and end offset. This offers its benefits (e.g. range comparisons are merely < and > operators instead of complex expressions).