Which of the following is a valid constraint in SQL? MCQ with Answer and Explanation

Question Report Error

Which of the following is a valid constraint in SQL?

A. PRIMARY KEY

B. FOREIGN KEY

C. All of the above

D. CHECK

Answer: Option C

Solution (By JKExamLibrary)

CHECK, PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL are all constraints in SQL.

This question belongs to: Computer Database Management System (DBMS)

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Practice More Database Management System (DBMS) Questions

Question #1 Report Error

In a Relational Database Management System (RDBMS), data is logically organized and stored in which form?

A. Tables

B. Graphs

C. Flat text files

D. Trees

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Correct Answer: Option A

Explanation:
In an RDBMS, data is organized into relations, which are logically represented as two-dimensional tables consisting of rows and columns.

This question belongs to: Computer Database Management System (DBMS)

Question #2 Report Error

What is the purpose of the COMMIT statement in SQL?

A. To save a point within a transaction

B. To permanently save all changes made in a transaction

C. To undo all changes made in a transaction

D. To start a new transaction

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Correct Answer: Option B

Explanation:
COMMIT finalizes a transaction, making all changes permanent in the database.

This question belongs to: Computer Database Management System (DBMS)

Question #3 Report Error

What is a self join?

A. Joining more than two tables

B. Joining a table with itself

C. Joining two different tables

D. Joining tables without a common column

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Correct Answer: Option B

Explanation:
A self join is a join where a table is joined with itself, often used to compare rows within the same table.

This question belongs to: Computer Database Management System (DBMS)

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