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Home -> Community -> Usenet -> c.d.o.misc -> Re: Duration Question
Hmm.. If there's a class that offers this, sign me up .. I might have
misstated it, because I'm pretty sure it's not that easy.
The idea is, with just the start, end, and duration, have a report that would show the following:
The maximum number of cars on the road, in the hour of:
hour 00 01 02 03 04 05 06 07 (AM) ......
------------------------------------------------
num cars 10 12 15 3 0 11 19 31 .......
So the idea is to have the report generate a 24 hour snapshot of the max numbers - each hour. As I write this I realize that the original question wasn't clear about the layout , but this is my goal. Is it still something that I could use count(*), between, group by? Do I need to do some kind of self join? The table is very large (millions of rows), so I'm also concerned about performance.
DA Morgan wrote:
> dave.howland_at_gmail.com wrote:
> > Okay, I guess I could have been more specific - how would one go about
> > doing it?
> > It seems like it would be one of those SQL tricks.
> > Michel Cadot wrote:
> >> <dave.howland_at_gmail.com> a écrit dans le message de news: 1165033982.461507.272230_at_80g2000cwy.googlegroups.com...
> >> | Hello everyone:
> >> |
> >> | I have a db table that contains three pieces of information ( let's say
> >> | I was tracking car trips), a start time(date), an end time(date) and a
> >> | duration(int) What I want to know (two things) (a) in every hour of
> >> | every day, is there a way that I could tell the maximum number of
> >> | concurrent cars on the road? (b) what is the total number of cars on
> >> | the road in each hour?
> >> |
> >> | Can this be done is SQL?
> >> |
> >>
> >> Yes.
> >>
> >> Regards
> >> Michel Cadot
>
>
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