All Questions
Tagged with rdbms normalization
6 questions
1
vote
1
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Why is the following decomposition into 2NF wrong?
Consider the relation R(A, B, C, D, E), with the functional dependencies being {BE->A, D->E}. What is R's decomposition in 2NF?
The answer is R1(D, E); R2(B, E, A); R3(B, C, D)
I've derived that ...
watson
-2
votes
2
answers
174
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Why is it a bad idea to have multiple values in a column in a relational database?
One problem I've found is slow database queries. If I had a table that had a column titled customer and another column titled grocery_items that contained multiple grocery items, then a simple query ...
2
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0
answers
183
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Understanding multivalued dependencies
This is my first time studying multivalued dependencies and there is a question that was posted by my lecturer as a class exercise. I have an answer, but I'm not 100% sure it was right. Please let me ...
- 21
2
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3
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1k
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A column value depends on the values of two other columns, of which exactly one is nullable
In the Person table, either the Citizen_IdentityID or the Foreigner_WorkPermitID will contain NULL marks.
The PersonID_ID holds either the value of the Citizen_IdentityID or Foreigner_WorkPermitID (...
- 111
0
votes
2
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4k
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Proper way to store lots of links?
I'm doing a small crawl over multiple sites and I have a lot of links which are represented by ID's (example.com/foo = 354).
I'm currently storing the link -> link references and the link text. So ...
- 109
2
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6
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Is normalization process needed?
Well after learning DBMS as a subject i got so many questions in mind. Normalization is one of them. As i learnt it there was a lot more confusion and i found that whatever we do in normalization ...
- 305