Is candidate key Same as key?

Question

Primary Key is a unique and non-null key which identify a record uniquely in table. A table can have only one primary key. Candidate key is also a unique key to identify a record uniquely in a table but a table can have multiple candidate keys. 27 нояб. 2019 г.

Is every key a candidate key?

Every table must have at least a single candidate key. A table can have multiple candidate keys but only a single primary key. Properties of Candidate key: It must contain unique values.

How is primary key different from candidate key?

The difference here is that a primary key acts as a minimal super key. Thus, a relation can only have one primary key. On the other hand, multiple candidate keys (two or more) can take place in any relationship. The attributes in a candidate key may contain a NULL value that opposes the primary key in it.

Can candidate key become primary key?

Each Candidate Key can qualify as Primary Key. Primary Key – A Primary Key is a column or a combination of columns that uniquely identify a record. Only one Candidate Key can be Primary Key. A CK is a set of columns that is unique and does not contain a smaller set of columns that is unique.

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