All questions of Database Management System (DBMS) for Computer Science Engineering (CSE) Exam

Components of a DBMS

A database management system (DBMS) is a software system that allows users to create, manipulate, and manage databases. It provides a structured way to store, retrieve, and manage data efficiently. The DBMS consists of various components that work together to ensure the smooth functioning of the system. The components of a DBMS include:

1. Data:
Data is the raw material that is stored in a database. It represents the facts, figures, and information that are organized and managed by the DBMS. Data can be of different types, such as text, numbers, dates, images, audio, and video.

2. Data Languages:
Data languages are used to interact with the database. They provide a set of commands and statements to define, manipulate, and retrieve data. There are mainly two types of data languages:

- Data Definition Language (DDL): DDL is used to define the structure and organization of the database. It includes commands to create, modify, and delete database objects like tables, views, indexes, and constraints.

- Data Manipulation Language (DML): DML is used to manipulate and retrieve data from the database. It includes commands to insert, update, delete, and query data from database tables.

3. Data Manager:
The data manager is the heart of the DBMS. It is responsible for managing the storage and retrieval of data from the database. The data manager performs the following functions:

- Data Storage: It manages the physical storage of data on disk or other storage devices. It ensures efficient allocation and retrieval of data, as well as data security and integrity.

- Data Retrieval: It retrieves data from the storage and presents it to the user or application. It uses various techniques like indexing, caching, and query optimization to improve data retrieval performance.

- Data Security: It ensures the security and integrity of the data by implementing access control mechanisms, encryption, and backup and recovery procedures.

- Data Concurrency: It manages concurrent access to the database by multiple users or applications. It ensures that transactions are executed in a consistent and isolated manner, avoiding conflicts and data anomalies.

- Data Integrity: It enforces data integrity constraints, such as primary key, foreign key, and check constraints. It ensures that the data stored in the database is consistent and accurate.

In summary, the components of a DBMS include data, data languages (DDL and DML), and the data manager. These components work together to provide a robust and efficient system for managing databases.

The correct answer is option 'C': Database application and the database.

Explanation:
The DBMS (Database Management System) acts as an interface between the database application and the database in an enterprise-class system. Let's break down the components involved:

1. Database Application:
A database application refers to the software program or set of programs that interact with the database. It is responsible for managing and manipulating the data stored in the database. The database application can be a custom-built application or a commercial software package.

2. Database:
A database is a structured collection of data that is organized and stored in a systematic manner. It can be a relational database, object-oriented database, or any other type of database depending on the requirements of the system. The database stores the actual data that is used by the application.

3. DBMS:
The DBMS is a software system that provides an interface for managing and interacting with the database. It acts as a mediator between the database application and the database. The main functions of a DBMS include data storage, data retrieval, data manipulation, and data security.

Role of DBMS as an interface:
The DBMS plays a crucial role in an enterprise-class system by acting as an interface between the database application and the database. Here's how it facilitates communication between these two components:

1. Data Storage and Retrieval:
The DBMS provides mechanisms for storing and retrieving data from the database. It manages the physical storage of data on disk and provides efficient algorithms for accessing the data based on user queries from the application.

2. Data Manipulation:
The DBMS allows the application to perform various operations on the data stored in the database. This includes inserting new data, updating existing data, deleting data, and querying the database to retrieve specific information. The DBMS ensures data integrity and consistency during these operations.

3. Data Security:
The DBMS enforces security measures to protect the data in the database. It provides mechanisms for user authentication, access control, and data encryption. It ensures that only authorized users can access and modify the data, thereby maintaining the confidentiality and integrity of the information.

In conclusion, the DBMS acts as a vital interface between the database application and the database in an enterprise-class system. It enables efficient storage, retrieval, manipulation, and security of data, ensuring seamless communication between the application and the underlying database.

What is information about data called

Mera data ans

Function of DELETE command:

Deleting a particular tuple from a relation using the DELETE command.

- Delete from r where P: This command is used to delete a particular tuple from a relation 'r' based on a condition 'P'.
- Clears entries from relation: The DELETE command does not clear all entries from the relation, instead, it targets specific tuples that satisfy the condition 'P'.
- Deletes relation: The DELETE command does not delete the entire relation, it only removes specific tuples that meet the condition specified in the WHERE clause.
- Deletes particular tuple from relation: The main function of the DELETE command is to delete a particular tuple or row from a relation based on the given condition.

Therefore, the correct function of the DELETE command with the given syntax is to delete a specific tuple from the relation 'r' that satisfies the condition 'P'.

Foreign Key and Primary Key Relationship

Foreign Key and Primary Key relationship in a database creates a network model between tables that connect them. A foreign key is a field or a set of fields in one table that refers to the primary key in another table. This relationship establishes a connection between the two tables, allowing for data integrity and efficient data retrieval.

1. Primary Key:
A primary key is a unique identifier for each record in a table. It ensures that each record in the table is uniquely identifiable and serves as a reference for other tables. The primary key constraint is used to enforce this uniqueness and is typically applied to one or more fields in a table.

2. Foreign Key:
A foreign key is a field or a set of fields in one table that refers to the primary key in another table. It establishes a link between the two tables, allowing for the enforcement of referential integrity. The foreign key constraint ensures that the values in the foreign key field(s) match the values in the referenced primary key field(s) or are NULL.

Network Model between Tables:

When a foreign key is combined with a primary key, it creates a network model between the tables that connect them. This network model represents the relationships between tables in a database.

1. One-to-One Relationship:
A foreign key can be used to establish a one-to-one relationship between two tables. In this type of relationship, each record in one table is associated with exactly one record in the other table. Example: Employee and EmployeeDetails tables, where each employee has unique details.

2. One-to-Many Relationship:
A foreign key can also establish a one-to-many relationship between two tables. In this type of relationship, each record in the primary table can be associated with multiple records in the related table. Example: Customer and Orders tables, where one customer can have multiple orders.

3. Many-to-Many Relationship:
A many-to-many relationship can be implemented using a junction table, which includes the primary keys of the two tables involved. The foreign keys in the junction table connect the primary keys of the related tables. Example: Student and Course tables, where each student can be enrolled in multiple courses, and each course can have multiple students.

Conclusion:

In summary, when a foreign key is combined with a primary key, it creates a network model between tables that connect them. This network model represents the relationships between tables, such as one-to-one, one-to-many, or many-to-many, and ensures data integrity and efficient data retrieval in a database.

DDL (Data Definition Language) is generally used for performing tasks like creating the structure of the relations and deleting relations in a database.

Explanation:

DDL stands for Data Definition Language, and it is a set of SQL commands used for defining the database schema. It allows users to create, modify, and delete database objects such as tables, views, indexes, and sequences. DDL statements are used to define the structure of the database and its objects.

Creating the Structure of Relations:

One of the main tasks performed by DDL is creating the structure of relations, i.e., creating tables. Tables are used to store data in a structured manner. With DDL, you can specify the name of the table, define the columns and their data types, set constraints, and define any indexes or keys necessary for the table.

For example, to create a table called "Employees" with columns such as "EmployeeID," "FirstName," and "LastName," you would use a DDL statement like:

```
CREATE TABLE Employees (
EmployeeID INT PRIMARY KEY,
FirstName VARCHAR(50),
LastName VARCHAR(50)
);
```

This statement creates a table named "Employees" with three columns: "EmployeeID" of type INT, "FirstName" of type VARCHAR(50), and "LastName" of type VARCHAR(50).

Deleting Relations:

DDL is also used for deleting relations, i.e., dropping tables from the database. When a table is no longer needed or if it needs to be recreated with different structure, the DROP TABLE statement can be used. This statement removes the specified table and all its associated data.

For example, to delete the "Employees" table created earlier, you would use the following DDL statement:

```
DROP TABLE Employees;
```

This statement removes the "Employees" table and all its data from the database.

In summary, DDL is used for creating the structure of relations (tables) and deleting relations (dropping tables) in a database. It is an essential part of database management and allows users to define and modify the structure of the database schema.

Explanation:

The given query:

SELECT name, course_id
FROM instructor, teaches
WHERE instructor_ID = teaches_ID;

is used to retrieve the names and course IDs of instructors who are teaching courses. The tables involved in this query are "instructor" and "teaches".

The options provided for replacing the given query are as follows:

a) Select name, course_id from teaches, instructor where instructor_id = course_id;
This option is incorrect because it is trying to select the name and course ID from the "teaches" and "instructor" tables without specifying the joining condition between them. The condition "instructor_id = course_id" is incorrect as it does not establish a proper relationship between the two tables.

b) Select name, course_id from instructor natural join teaches;
This option is correct because it uses the "natural join" operation to join the "instructor" and "teaches" tables. The "natural join" operation automatically matches the columns with the same name in the two tables and returns the result. In this case, it will match the "instructor_id" column from the "instructor" table with the "teaches_id" column from the "teaches" table.

c) Select name, course_id from instructor;
This option is incorrect because it only selects the name and course ID from the "instructor" table without considering the relationship with the "teaches" table. It will not provide the desired result of retrieving the names and course IDs of instructors who are teaching courses.

d) Select course_id from instructor join teaches;
This option is incorrect because it only selects the course ID from the "instructor" table without selecting the instructor's name. It also does not specify the joining condition between the "instructor" and "teaches" tables.

Therefore, the correct option to replace the given query is Option B - Select name, course_id from instructor natural join teaches; as it properly joins the "instructor" and "teaches" tables and retrieves the desired columns.

Feature of DBMS: Single-user Access only

One of the features of a DBMS (Database Management System) is that it allows for multiple users to access and manipulate the data stored in the database. However, it also provides the option to restrict access to a single user or a group of users.

Explanation:

1. Security:
By limiting access to a single user, the DBMS provides higher security to the data stored in the database. This is useful in cases where sensitive information is stored in the database, and only authorized personnel should be able to access it.

2. Control:
Single-user access also allows for better control over the database. This means that the DBA (Database Administrator) can have complete control over the database operations and ensure that there are no conflicting changes made by multiple users.

3. Performance:
Single-user access can also improve the performance of the database. Since there is no contention for resources, the database operations can be executed more efficiently and with less overhead.

4. Simplicity:
In some cases, a single-user access can also simplify the design and implementation of the database. For example, if the database is intended to be used by a single application, there may not be a need for complex security mechanisms and multi-user support.

Conclusion:

Overall, single-user access is a useful feature of a DBMS that provides improved security, control, performance, and simplicity in certain cases. However, it is important to note that in most cases, a DBMS is designed to support multiple users, and single-user access should be used only when necessary.

Database Functions

A database is an organized collection of data that is used to store and retrieve information efficiently. It plays a crucial role in managing and manipulating data for various purposes. However, not all tasks associated with databases can be classified as functions of the database. Let's explore the given options in detail to understand which one is not a function of the database.


One of the primary functions of a database is to manage stored data. This includes creating and maintaining the structure of the database, defining tables and their relationships, and ensuring data integrity and consistency. The database provides mechanisms to store, organize, and retrieve data efficiently.


Manipulating data is another important function of a database. It involves performing operations like inserting, updating, and deleting data in the database. With the help of SQL (Structured Query Language) statements, users can manipulate data to meet their specific requirements. This function allows users to modify the contents of the database based on their needs.


Ensuring the security of stored data is a critical function of a database. It involves implementing measures to protect the data from unauthorized access, accidental loss, or corruption. Databases provide security features such as user authentication, access control, encryption, and backup and recovery mechanisms. These security measures help maintain the confidentiality, integrity, and availability of the data.


Analyzing code, as mentioned in option D, is not a function typically associated with a database. While databases can store code, such as stored procedures or triggers, their primary purpose is not to analyze or execute code directly. Code analysis is usually performed by separate tools or programming environments that specialize in code analysis and debugging.

Therefore, the correct answer is option D - Analyzing code. While databases can store and execute code, analyzing code is not a core function of a database.

Explanation:

A weak entity set is an entity set that does not have sufficient attributes to form a primary key on its own. It relies on a strong entity set to provide a partial or total key.

To understand which set should be associated with a weak entity set to be meaningful, let's consider the options:

a) Neighbour set: This set refers to the neighboring entities of the weak entity. While it may be related to the weak entity, it does not necessarily provide a key for the weak entity set. Therefore, it is not the correct option.

b) Strong entity set: A strong entity set is an entity set that has a primary key on its own and does not depend on any other entity set. Since a weak entity set relies on a strong entity set, associating it with a strong entity set is necessary to form a meaningful relationship. However, it is not the correct option for this question.

c) Owner set: The owner set refers to the entity set that owns or has control over the weak entity set. While the owner set may have a relationship with the weak entity set, it does not provide a key for the weak entity set. Therefore, it is not the correct option.

d) Identifying set: An identifying set is a set of attributes in a strong entity set that uniquely identifies each entity in the weak entity set. This means that the identifying set is used to form a partial or total key for the weak entity set. Therefore, associating the weak entity set with the identifying set is necessary for it to be meaningful.

Conclusion:

In order for a weak entity set to be meaningful, it needs to be associated with the identifying set from a strong entity set. This ensures that the weak entity set can be uniquely identified and related to the strong entity set.

Data Definition Language (DDL)

Data Definition Language (DDL) is a subset of SQL commands used to define and manipulate the structure of database objects. It allows users to create, modify, and delete database objects such as tables, views, indexes, and sequences. In the context of Oracle Structures, DDL commands are used to manipulate tables and other related objects.

Key DDL Commands

Some of the key DDL commands used to manipulate Oracle Structures include:

1. CREATE: The CREATE command is used to create new database objects. For example, CREATE TABLE is used to create a new table in the database.

2. ALTER: The ALTER command is used to modify the structure of existing database objects. For example, ALTER TABLE is used to add, modify or delete columns in a table.

3. DROP: The DROP command is used to delete existing database objects. For example, DROP TABLE is used to delete a table from the database.

4. TRUNCATE: The TRUNCATE command is used to delete all the data from a table while keeping the table structure intact.

5. RENAME: The RENAME command is used to rename an existing database object. For example, RENAME TABLE is used to rename a table.

6. COMMENT: The COMMENT command is used to add comments or descriptions to database objects. For example, COMMENT ON TABLE is used to add a comment to a table.

Conclusion

In conclusion, the subset of SQL commands used to manipulate Oracle Structures, including tables, is the Data Definition Language (DDL). DDL commands such as CREATE, ALTER, DROP, TRUNCATE, RENAME, and COMMENT are used to define, modify, and delete database objects. These commands play a crucial role in managing the structure of the database and ensuring data integrity.

Data Types That Can be Stored in a Database

A database is an organized collection of data. It can store various types of data, including:

1. Image-Oriented Data:
Images can be stored in a database, and it is called Image-oriented data. For example, a company that sells products can store the product images in a database. Image-oriented data is usually stored in binary format.

2. Text:
Text is the most common type of data that can be stored in a database. The text can be in the form of a single word or a complete document. It includes all the textual information that can be stored in a database.

3. Files Containing Data:
A database can store files that contain data. These files can be of any format, including PDF, Word, Excel, and others. For example, a company can store its financial reports in a database.

4. Audio and Video Data:
A database can also store audio and video data. For example, a music streaming website can store its songs in a database. Video-sharing websites can store videos in a database.

Conclusion:
In conclusion, a database can store various types of data, including text, files containing data, audio, and video data, and image-oriented data. The type of data that can be stored in a database depends on the requirements of the application.

Introduction:
In the field of database management, normalization is a technique used to organize data in a structured and efficient manner. It involves structuring the database tables to eliminate redundancy and ensure data integrity. Normalization is achieved by dividing larger tables into smaller, more manageable tables and establishing relationships between them.

Explanation:
Normalization is divided into several normal forms, including 1NF, 2NF, 3NF, 4NF, and 5NF. Each normal form has specific rules and requirements that need to be met for a database to be considered normalized.

1. First Normal Form (1NF):
1NF is the most basic form of normalization. In this form, the data is organized into tables, and each column contains only atomic values (i.e., indivisible). There should be no repeating groups or arrays within a single column.

2. Second Normal Form (2NF):
2NF builds upon 1NF and introduces the concept of functional dependencies. In this form, all non-key attributes must be functionally dependent on the entire primary key. This means that each non-key attribute should depend on the entire primary key, not just a part of it.

3. Third Normal Form (3NF):
3NF further refines the normalization process by eliminating transitive dependencies. In this form, all non-key attributes must be functionally dependent on the primary key and not on other non-key attributes. Transitive dependencies occur when a non-key attribute depends on another non-key attribute, which in turn depends on the primary key.

4. Fourth Normal Form (4NF):
4NF focuses on eliminating multi-valued dependencies. In this form, the database tables are structured in such a way that there are no non-trivial multi-valued dependencies between attributes. A multi-valued dependency occurs when a set of attributes depends on another set of attributes, independent of the primary key.

5. Fifth Normal Form (5NF):
5NF, also known as Project-Join Normal Form (PJNF), is the highest level of normalization. It deals with eliminating join dependencies. A join dependency occurs when a table can be decomposed into multiple tables, each having a subset of attributes, and still be able to reconstruct the original table through a join operation.

Answer:
Out of the given options, 4NF is the correct answer because it specifically deals with multi-valued dependencies. In 4NF, the database tables are structured to eliminate non-trivial multi-valued dependencies between attributes. The other options (2NF, 3NF, and 5NF) focus on different types of dependencies but not specifically on multi-valued dependencies.

DBMS Technology for Maintaining Transactional Integrity and Consistency

Transactional integrity and consistency are essential for any database management system. Here are the different technologies used by DBMS to maintain them:

1. Locks:
- DBMS uses locks to maintain transactional integrity and consistency.
- Locks are used to prevent multiple users from accessing the same data simultaneously.
- It ensures that only one user can modify the data at a time, avoiding any inconsistency or data corruption.

2. Pointers:
- Pointers are not used to maintain transactional integrity and consistency in a DBMS.
- They are used in programming languages to store the memory address of a variable or function.

3. Cursors:
- Cursors are not used to maintain transactional integrity and consistency in a DBMS.
- Cursors are used to traverse through the records retrieved by a query.

4. Triggers:
- Triggers are used to maintain transactional integrity and consistency in a DBMS.
- They are special procedures that are executed automatically when a specific event occurs.
- Triggers are used to enforce business rules, data validation, and maintain referential integrity.

Therefore, option 'C' is correct as locks are used to maintain transactional integrity and consistency in a DBMS.

**Procedural language among the following is Relational Algebra**

Relational Algebra is a procedural query language that is used to manipulate and retrieve data from relational databases. It provides a set of operations that can be used to perform various tasks on the database.

**Explanation:**

Relational Algebra is a procedural language because it specifies a series of operations that need to be performed step by step in order to achieve the desired result. It is used to define the sequence of operations that need to be executed on a database to retrieve the desired data.

**Domain Relational Calculus and Tuple Relational Calculus:**

Domain Relational Calculus and Tuple Relational Calculus are both non-procedural query languages. They are used to specify what data needs to be retrieved from a database, but they do not specify how the data should be retrieved.

In Domain Relational Calculus, the queries are expressed in terms of variables and quantifiers, and the result is a set of values that satisfy the given conditions.

In Tuple Relational Calculus, the queries are expressed in terms of tuples, and the result is a set of tuples that satisfy the given conditions.

Both of these languages are declarative languages, which means that they specify what needs to be done rather than how it should be done.

**Query Language:**

Query language is a broad term that refers to any language used to communicate with a database. It can include both procedural and non-procedural languages. SQL (Structured Query Language) is a popular query language that is used to interact with relational databases.

While SQL is primarily a non-procedural language, it does have some procedural elements, such as the ability to use control structures like loops and conditional statements.

**Conclusion:**

Among the given options, Relational Algebra is the procedural language. It provides a set of operations that need to be performed step by step to manipulate and retrieve data from relational databases. Domain Relational Calculus, Tuple Relational Calculus, and Query Language (such as SQL) are either non-procedural or have a mix of procedural and non-procedural elements.