An instance of relational schema R (A, B, C) has distinct values of A including NULL values. Which one of the following is true?
| A. | A is a candidate key |
| B. | A is not a candidate key |
| C. | A is a primary Key |
| D. | Both (A) and (C) |
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Option: B Explanation : Click on Discuss to view users comments. |
Consider the join of a relation R with relation S. If R has m tuples and S has n tuples, then the maximum size of join is:
| A. | mn |
| B. | m+n |
| C. | (m+n)/2 |
| D. | 2(m+n) |
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Option: A Explanation : Click on Discuss to view users comments. |
The natural join is equal to :
| A. | Cartesian Product |
| B. | Combination of Union and Cartesian product |
| C. | Combination of selection and Cartesian product |
| D. | Combination of projection and Cartesian product |
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Option: C Explanation : Click on Discuss to view users comments. Pushpraj Singh said: (2:46pm on Tuesday 12th March 2013)
The right answer is C not DRef: Korth Book
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Which one of the following is not true for a view:
| A. | View is derived from other tables. |
| B. | View is a virtual table. |
| C. | A view definition is permanently stored as part of the database. |
| D. | View never contains derived columns. |
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Option: C Explanation : Click on Discuss to view users comments. Geetu said: (10:34pm on Friday 12th April 2013)
I dont this is a correct answer...as the database stores the view definition only. is this wrong that view definition is stored in database?
Javid said: (9:43am on Sunday 4th March 2018)
Correct answer is D
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A primary key if combined with a foreign key creates
| A. | Parent-Child relationship between the tables that connect them. |
| B. | Many to many relationship between the tables that connect them. |
| C. | Network model between the tables that connect them. |
| D. | None of the above. |
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Option: A Explanation : Click on Discuss to view users comments. |
