Primary key helps differentiate the data in a table which contains multiple occurrences of any value in columns. Besides that it is considered good programming practice which will ensure that there...
There is two difference between them.
1. The not null constraint is by default added to primary key, it means, primary key attribute cannot accept null values, whereas, the attribute declared as...
primary key: primary creates a clustered index on the column and it doesn't allow null values.unique key: unique key creates non clustered index by default.it allows "one null value".foreign key: A...