Subject | Re: Calculating time |
---|---|

Author | Svein Erling Tysvær |

Post date | 2004-09-22T12:18:13Z |

Hi Primoz.

The type 'time' is not a duration, but the exact point in time (e.g.

3:15 am). It makes sense to ask questions like "I came in 1am and left

3am. How long time did I spend there?" It doesn't make any sense to

say "I came at 1am and left at 3am. How long time did I spend there if

I also subtract 0:30am from the result?". Subtracting a point in time

from a duration is as sensible as subtracting weight from litres -

it's incompatible and cannot be done.

If your fields contain duration, then don't use time fields at all.

Or, if the first two really are a point in time, then keep the third

as an integer value:

<Time1>-<Time2>-<number of seconds>, or in your case:

3:00:00 - 1:00:00 - 1800

HTCUC (Hope This Clears Up Confusion),

Set

The type 'time' is not a duration, but the exact point in time (e.g.

3:15 am). It makes sense to ask questions like "I came in 1am and left

3am. How long time did I spend there?" It doesn't make any sense to

say "I came at 1am and left at 3am. How long time did I spend there if

I also subtract 0:30am from the result?". Subtracting a point in time

from a duration is as sensible as subtracting weight from litres -

it's incompatible and cannot be done.

If your fields contain duration, then don't use time fields at all.

Or, if the first two really are a point in time, then keep the third

as an integer value:

<Time1>-<Time2>-<number of seconds>, or in your case:

3:00:00 - 1:00:00 - 1800

HTCUC (Hope This Clears Up Confusion),

Set

--- In firebird-support@yahoogroups.com, "Planles" wrote:

> Hi!

>

> Subtracting two times fields we get seconds in decimal format.

> This doesn't bother me anymore, if I want to subtract two time

> fields.

>

> How can I substract 3 fields: time1 - time2 - time3

>

> example:

> 3:00:00 - 1:00:00 - 0:30:00 = 1:30:00 (or 5400 sec)