can anyone answer me what is the basic difference between primary key, superkey, candidate key, composite key?

Question

in simple language & when they are used?Advantages & disadvantages?

Answer 1

http://stackoverflow.com/questions/6951052/key-superkey-minimal-superkey-candidate-key-primary-key-differences

Answer 2

candidate key - is a minimal superkey which can be used as a primary key. primary key- has unique vallue for each record. is a candidate key that you have chosen as superkey. alternate keys- ?? dnt know about that hope this might help.

Answer 3

A primary key is your key for the front door. Always bring it with you as it's used most often.

A super key is your key for the back door. Sometimes you need it like when the front door is broken. But you usually use the front door, so it is optional whether to bring it with you.

A candidate key is a spare key for the front door. Simple as that.

A composite key is a combination of a primary and a candidate key. It is very complicated to explain what this means.

Answer 4

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