primary key:- The attribute or combination of attributes
that uniquely identifies a row or record.
Foreign Key:- an attribute or combination of attribute in a
table whose value match a primary key in another table.
Composite key:- A primary key that consistsof two or more
attributes is known as composite key
candidate key:- is a column in a table which has the
ability to become a primary key.
Alternate Key:- Any of the candidate keys that is not part
of the primary key is called an alternate key.
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