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DBMS KEY DEFINITION
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dear friends whats exactly the "SUPER KEY" AND "CANDIDATE KEY" in terms of dbmsTuesday, February 27, 2007 2:25 PM
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Super Key : A column or set of columns that uniquely identifies a row within a table.
Candidate Key : In the relational model a candidate key of a relation is a set of attributes of that relation such that (1) in all instances of that relation it holds that there are no two distinct tuples with the same values for these attributes and (2) there is not a proper subset for which (1) holds. Since a superkey is defined as a set of attributes for which (1) holds we can also define candidate keys as minimal superkeys, i.e., superkeys of which no proper subset is also a superkey
Wednesday, February 28, 2007 6:42 PM 
ya sanket is right...but u can easily get these kinda basic defn's through googling...Tuesday, March 6, 2007 3:48 PM

A super key is a set of columns within a table whose values can be used to uniquely identify a row.
A candidate key is a minimal set of columns necessary to identify a row,
Tuesday, March 6, 2007 6:08 PM 
A superkey is defined in the relational model as a set of attributes of a relation variable (relvar) for which it holds that in all relations assigned to that variable there are no two distinct tuples (rows) that have the same values for the attributes in this set. Equivalently a superkey can also be defined as a set of attributes of a relvar upon which all attributes of the relvar are functionally dependent.
In the relational model, a candidate key of a relvar is a set of attributes of that relvar such that
(1) at all times it holds in the relation assigned to that variable that there are no two distinct tuples with the same values for these attributes and
(2) there is not a proper subset for which (1) holds.Saturday, March 10, 2007 8:52 AM 
dear friend its easy to find results through google but definitions r not understandable thats why i needed help, but anyways thanks for the suggestion.Saturday, March 10, 2007 3:37 PM
All replies

Super Key : A column or set of columns that uniquely identifies a row within a table.
Candidate Key : In the relational model a candidate key of a relation is a set of attributes of that relation such that (1) in all instances of that relation it holds that there are no two distinct tuples with the same values for these attributes and (2) there is not a proper subset for which (1) holds. Since a superkey is defined as a set of attributes for which (1) holds we can also define candidate keys as minimal superkeys, i.e., superkeys of which no proper subset is also a superkey
Wednesday, February 28, 2007 6:42 PM 
ya sanket is right...but u can easily get these kinda basic defn's through googling...Tuesday, March 6, 2007 3:48 PM

A super key is a set of columns within a table whose values can be used to uniquely identify a row.
A candidate key is a minimal set of columns necessary to identify a row,
Tuesday, March 6, 2007 6:08 PM 
A superkey is defined in the relational model as a set of attributes of a relation variable (relvar) for which it holds that in all relations assigned to that variable there are no two distinct tuples (rows) that have the same values for the attributes in this set. Equivalently a superkey can also be defined as a set of attributes of a relvar upon which all attributes of the relvar are functionally dependent.
In the relational model, a candidate key of a relvar is a set of attributes of that relvar such that
(1) at all times it holds in the relation assigned to that variable that there are no two distinct tuples with the same values for these attributes and
(2) there is not a proper subset for which (1) holds.Saturday, March 10, 2007 8:52 AM 
dear friend its easy to find results through google but definitions r not understandable thats why i needed help, but anyways thanks for the suggestion.Saturday, March 10, 2007 3:37 PM