nptel assignment sql

Question

Comments

The table name is student and all of the options are creating the table "employee".

Also none of the options have the last field name as "courseid" instead they have "age".

The question is not matching with the options!  :/

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the question is more focus on which can be primary key. ( i hope courseid is mistakenly print... it should be age)

By observing the tuples we can say that, first name could be use as key ===> option C is matching

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Shaik Masthan

Then why not B?

If you say option C then there is no NOT NULL constraint on firstname. So firstname can be NULL but composite Primary key i.e. (firstname,lastname) can't have NULL value in any of the attributes.

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@MiNiPanda

yes, it's my mistake ( i assumed they given NOT NULL constraint )

yes it's option B only.