what is candidate key & primary key,different b/t the two?

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what is candidate key & primary key,different b/t the two?..

Answer / naz

A Candidate Key can be any column or a combination of
columns that can qualify as unique key in database. There
can be multiple Candidate Keys in one table. Each Candidate
Key can qualify as Primary Key.

A primary key is the column that uniquely identifies a
record. A primary key should be UNIQUE and never be NULL.

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what is candidate key & primary key,different b/t the two?..

Answer / uday shankar dokku

candidate key: when we reduce unnecessary columns from a
super key it is called as candidate key
primary key: primary key is a constraint, in a table
there is only one primary key,a primary key is simple or
composite, a simple primary key is based on one column which
can be specified either inline outline of the constraint,a
composite primary key is based on (2-32)columns which can
be specified only out line of the constraint,a primary dose
not allows duplicates.

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what is candidate key & primary key,different b/t the two?..

Answer / parijatha

there is no difference between the candidate and primary key
as both derives all other attributes in the relation.The
concept of primary key came into account to make the search
easy the is whenever a candidate key is declared as primary
key the primary key attribute gets sorted which reduces the
response time

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