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Apr
11
answered Given the functional dependencies of a relation is there more then one way to normalize it?
Mar
31
awarded  Yearling
Mar
21
comment Confusion with Foreign Keys
There's no reason in principle why primary key attributes shouldn't be foreign keys.
Mar
5
comment Column suitable for natural key?
@mircale, my point was that the reason for key constraints is to guarantee that infomration is not duplicated. If you don't enforce a natural key on some attribute then the values of that attribute may be duplicated on multiple tuples with different surrogate key values. That is apparently not what is wanted here.
Mar
3
answered Column suitable for natural key?
Feb
25
answered Is matriculation number a good primary key?
Jan
4
comment Primary Key Question
"if I have a key of FirstName, LastName, Email on my Student table, and then have to repeat that information in my Classes table then I'm duplicating data in that table and breaking one of the normal forms. Is that not correct?" That is not correct. In any case it's a poor example because it seems highly unlikely that firstname and lastname would be part of a key for students in any real or practical sense.
Nov
25
revised Platform independent select ordered by primary key
added 935 characters in body
Nov
25
revised Platform independent select ordered by primary key
deleted 1 characters in body
Nov
25
answered Platform independent select ordered by primary key
Nov
1
comment If all variables are a subset of the candidate key, is the database design 5NF?
Damir, you are right and my answer is wrong. I don't know what I was thinking of - BCNF maybe. Thanks anyway.
Oct
31
comment Is normalization process needed?
Perhaps it would be better to say that we should normalize the logical structure of the database. The phrase "logical model" is often (mis)understood to mean merely a preliminary design for a database rather than something actually existing in a database system. The important point surely is that what you implement ought to be normalized, not just what you sketch on paper :)
Jul
31
awarded  Nice Answer
Jun
16
comment how to convert a table into second normal form
Without any explanation of what dependencies the table is supposed to satisfy all anyone can do is make guesses based on the attribute names.
May
13
awarded  Caucus
May
10
answered Can a surrogate key and a primary key be in the same table?
May
2
answered Database design - People and Organisations
Mar
31
awarded  Yearling
Dec
4
comment The four properties of a primary key
Perhaps you were taught wrong. Those four conditions are neither necessary nor sufficient to make a key. Keys must be irreducibly unique (a minimal superkey) and non-nullable. Non-partial dependence is a requirement of 2nd Normal Form but not a fundamental requirement of keys. Indexing also has nothing to do with whether a set of attributes qualify as a key or not.
Jul
18
comment Primary key should be chosen so as attributes never change?
You can't have read what I wrote. I was not "praising" anything. I've certainly changed surrogate key values plenty of times. In fact I'm surprised if you haven't encountered the need to update surrogate keys. Anyway, the question is about keys in general, not just surrogates. If you meant your answer to apply only to surrogate keys then you ought to say so.