Question

what is primary key? how is it different from foreign key? ​

Answer 1

Answer:

In the relational model of databases, a primary key is a specific choice of a minimal set of attributes (columns) that uniquely specify a tuple (row) in a relation (table). Informally, a primary key is "which attributes identify a record", and in simple cases are simply a single attribute: a unique id.Primary key uniquely identify a record in the table. Foreign key is a field in the table that is primary key in another table. By default, Primary key is clustered index and data in the database table is physically organized in the sequence of clustered index

Explanation:

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Answer 2

Primary key :- On the Design tab, in the Tools group, click Primary Key. A key indicator is added to the left of the field or fields that you specify as the primary key.

Differences :- Primary key uniquely identify a record in the table. Foreign key is a field in the table that is primary key in another table. By default, Primary key is clustered index and data in the database table is physically organized in the sequence of clustered index.