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Database Management Systems

Description: This test contains some conceptual questions on databese management system.
Number of Questions: 15
Created by:
Tags: Oracle Time and Work IT Companies Database
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Which among the following SQL commands is used to delete a table from a database?

  1. DROP

  2. DELETE

  3. TRUNCATE

  4. REMOVE

  5. ERASE TABLE

Show answer
Correct Option: A
Explanation:

This option is correct as DROP TABLE command is used to remove a table definition and all data.

Which of the following SQL queries is not a DDL command?

  1. Alter

  2. Revoke

  3. Grant

  4. Update

  5. Drop

Show answer
Correct Option: D
Explanation:

This option is correct as DDL statements define the structure of the database but Update command changes the data in the database.

Which of the following statements is a function of CREATE TABLE command?

  1. It is used to add an integrity constraint to a table.

  2. It is used to redefine a column of the table.

  3. It is used to change a table's storage characterstics.

  4. It is used to create tables and definine columns.

  5. It enables or disables integrity constraints.

Show answer
Correct Option: D
Explanation:

This option is correct as CREATE TABLE command creates a table in the database.

Which of the following SQL queries is not a DML statement?

  1. Delete

  2. Select

  3. Create

  4. Insert

  5. Update

Show answer
Correct Option: C
Explanation:

Create is a DDL statement as this statement defines the structure of a database.

Which SQL command is used to remove privileges given to a user?

  1. TRIGGER

  2. CREATE VIEW

  3. UPDATE

  4. GRANT

  5. REVOKE

Show answer
Correct Option: E
Explanation:

The REVOKE command revokes previously granted privileges from one or more roles.

Which of the following methods is used for protecting data in the data communication system?

  1. Data encryption

  2. Data integrity

  3. Data encapsulation

  4. Data redundancy

  5. Polymorphism

Show answer
Correct Option: A
Explanation:

This option is correct as data encryption is the most effective way to achieve data security. It is used to protect data by encrypting it with a secret key.

Which of the following commands is used to give access of database objects to other users?

  1. REVOKE

  2. DROP

  3. INSERT

  4. GRANT

  5. ALTER

Show answer
Correct Option: D
Explanation:

SQL GRANT is a command used to provide access or privileges of the database objects to other users.

Which of the following commands is used to create a trigger?

  1. CREATE TRIGGER

  2. CREATE VIEW

  3. CREATE TABLESPACE

  4. GRANT

  5. CREATE SYNONYM

Show answer
Correct Option: A
Explanation:

This option is correct as CREATE TRIGGER command is a SQL statement that creates a trigger to the database schema.

Which of the following SQL functions is used to find the average of a given record?

  1. AVG

  2. MIN

  3. MAX

  4. SUM

  5. SQRT

Show answer
Correct Option: A
Explanation:

This option is correct as AVG is a predefined SQL function that is used to calculate the average of a given record.

Which of the following statements is false?

  1. A table in 1st normal form contains no repeating groups.

  2. A table in 2nd normal form contains no partial functional dependency.

  3. 3 NF removes transitive functional dependency.

  4. 3 NF is equivalent to BCNF.

  5. BCNF is a special case of 3 NF.

Show answer
Correct Option: D
Explanation:

This option is false as 3NF and BCNF are equivalent only if BCNF contains only one candidate key.

Which of the following commands is a transaction control language?

  1. ALTER

  2. ROLLBACK

  3. GRANT

  4. DROP

  5. REVOKE

Show answer
Correct Option: B
Explanation:

This option is correct as transaction control commands manage the changes made by data manipulation commands.

Which of the following keywords is used to display only the unique entries of the column?

  1. WHERE

  2. DISTINCT

  3. SELECT

  4. LIKE

  5. GROUP BY

Show answer
Correct Option: B
Explanation:

This option is correct as this distinct keyword selects only those values that are unique.

Which of the following is a key constraint that is used to uniquely identify each row?

  1. PRIMARY KEY

  2. FOREIGN KEY

  3. COMPOSITE KEY

  4. ALTERNATE KEY

  5. DEFAULT

Show answer
Correct Option: A
Explanation:

This option is correct as primary key constraint does not allow duplicacy of data. Hence, it uniquely identifies each row in the table.

Which of the following can be used to retrieve data from a database?

  1. Stack

  2. Queue

  3. Linked list

  4. Query

  5. Data structure

Show answer
Correct Option: D
Explanation:

This option is correct because a query is a request for information from a database.

What is the meaning of an oval shape in an E-R diagram?

  1. Entity set

  2. Attributes

  3. Straight line

  4. Diamond

  5. Dotted oval

Show answer
Correct Option: B
Explanation:

This option is correct as in an entity relationship model, circles or ovals are designated to represent the attributes of the entity set.

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