Re: Functional dependencies
От | Darren Duncan |
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Тема | Re: Functional dependencies |
Дата | |
Msg-id | 4DF7A87D.1080206@darrenduncan.net обсуждение исходный текст |
Ответ на | Functional dependencies (Alpha Beta <dzjitaru@gmail.com>) |
Ответы |
Re: Functional dependencies
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Список | 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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