> At 06:53 PM 2/10/2001 +0100, Arnaldo wrote:
> > > >I do:
> > > >Select SUM( TIMEFIELD ), but cannot find a result.
> The error was :
> Statement failed, SQLCODE = -901
> data type not supported for arithmetic
Yes. I got it.
> >I have a field in which i store a difference from two fields.
> The difference between two times is not a time, it's a duration.
> The time datatype represents an instant in time, not a length of
> time. You wouldn't expect to sum two dates, right? This is the
> same thing. What do you get if you add eight o'clock in the
> morning to five o'clock in the afternoon? Cognitive dissonance.
> The time datatype is not closed over addition and
> subtraction. Multiplication and division are not
> defined for time. Duration is different. If you
> add one duration to another you get another duration.
> 5 hours + 6 hours = 11 hours
> 6 hours - 5 hours = 1 hour
> 4 hours * 4 = 16 hours
> 4 hours / 12 = .333 hours
> Duration behaves like other numeric types.
> Time is different.
> 07:30 + 3 = 10:00
> A time plus a number produces a time. The "3" is
> a number representing a duration of three hours.
> 12:00 - 8:00 = 4
> A time subtracted from a time produces a number -
> that's not four o'clock in the morning, but a
> duration of 4 hours.
> >So in this field I have: 7.30. in the second field : 8.30
> >These are the hours they have worked.
> >Now I MUST SUM all the Working Hours of this field.
> >so this two values must give 16.00 working hours.
> Use a numeric datatype to hold duration - hours worked,
> that sort of thing.
> We have answers.
Ann. Thanks for the reply.
I have already done what You write, but with no success.
I'll try another time, with more luck, I hope.