| From: | Darren Duncan <darren(at)darrenduncan(dot)net> |
|---|---|
| To: | Alpha Beta <dzjitaru(at)gmail(dot)com> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Functional dependencies |
| Date: | 2011-06-14 18:29:17 |
| Message-ID: | 4DF7A87D.1080206@darrenduncan.net |
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| Thread: | |
| Lists: | pgsql-general |
Alpha Beta wrote:
> Hi list, (newbie with databases)
>
> I was looking out in net about how can we determine or find all
> functional dependencies in a relational database, but didn't find.
>
> So can please anyone here tell me if functional dependecies for each
> table of a relational database can be found explicitly or
> we need algorithms for it or any other way?
>
> Best regards!
Look for pairs of columns/attributes X and Y (or X may be a set of
columns/attrs) where, for every row/tuple having the same value for X, the
row/tuple always has the same value for Y. In this situation, for the data you
have at least, there would seem to be a relationship where X determines Y and Y
depends on X. Use an algorithm that does this looking for pairs. -- Darren Duncan
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