Database Management System Questions and Answers PDF
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database management system questions and answers pdf
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What is DBMS?
Database Management System (DBMS) is a system software such as MySQL, or Oracle that is used to manage and create databases.
With the help of DBMS, any user can create, read, update and delete data in the database.
It mainly provides the interface between the database and the end user or application programs to ensure that the data is consistently organized and easily accessible.
When it receives a request for data from an application, it instructs the operating system to provide that specific data. It helps users or applications to store or retrieve data Read More
What is database
A database is an organized collection of structured information. In simple words, the systematic collection of data is called a "Database". That is because it is made very systematic. So that the data can be easily accessed, managed, and updated. The basic function of the database is to make data management easy.
What is SQL
The full name of SQL is Structured Query Language. It has been designed to insert and modify in Relational Database System.
What is Database System
The collection of a Database and DBMS together is called Database System. With its help, we can easily do many things like:-
With the help of a Database System, we are able to store the data easily, and due to this, there is never any error of Data Redundancy and Data Inconsistency.
With its help, data can be easily extracted from the database with the help of DBMS, so with the help of the combination of Database and DBMS (Database System), we can easily access, store, and retrieve the data with accuracy and security.
What are the advantages of DBMS
- redundancy control
- Restriction for unauthorized access
- Provides multiple user interfaces
- Provides backup and recovery
- Enforces integrity constraints
- Ensure data consistency
- Easy accessibility
What is a Checkpoint in DBMS?
Checkpoint in DBMS is a type of mechanism in which all the previous logs are removed from the system and they are permanently stored in the storage disk. There are two ways to recover and maintain ACID (Atomicity, Consistency, Isolation, and Durability) properties in DBMS:- (i) maintaining a log of each transaction and (ii) maintaining shadow pages.
So when we talk about a log-based recovery system then the concept of checkpoint comes in front of us. Checkpoints are points to which the database engine can recover after a crash as a specified minimum point from where transaction log records are used to recover all data up to the crash point.
When do checkpoints come in DBMS?
With the help of Checkpoint, we reduce our work in case of restarting after a crash in DBMS. The use of checkpoints works for the recovery of the database after each system crash. A checkpoint is used in a log-based recovery system.
Whenever a system crash occurs, after restarting the system, we do not have to start every transaction from the beginning, rather we can start it from the checkpoint.
What is Transparent DBMS?
This is the type of DBMS in which the physical structure can be hidden from the user. Physical structure or physical data can be understood like the memory manager of DBMS, it describes how the data is stored in Disk.
What is RDBMS?
Its full name is Relational Database Management Systems. It is used to maintain the index and data records in the table. It is a type of DBMS that is used to identify and understand the structure of data related to pieces of data in the database.
RDBMS is the system that enables you to operate a relational database for various operations like- update, insert, delete, and so on with the least difficulties. RDBMS most of the time uses SQL language as it is easily understood and used frequently.
What are the different types of DBMS?
Relational DBMS (RDBMS): - In this type of DBMS, such a structure is used, with the help of which you can access a piece of data in relation to another piece of data in the database.
Hierarchical DBMS: - As you can understand from the name itself, the shape of this type of DBMS is similar to a tree, in which nodes represent its records while the branches of this tree represent fields.
Network DBMS:- This type of DMBS supports many relations and multiple member records can be linked in it.
Object-Oriented DBMS:- It uses small individual software called objects to store the pieces of data and to give instructions for the operations to be done with the data.
Which languages are used in DBMS?
There are four types of languages used in DBMS.
DDL (Data Definition Language): - This type of language contains commands that are used to define the database.
DML (Data Manipulation Language): - It is used for commands to manipulate data in the database.
DCL (Data Control Language): - It is used for commands related to user permission and control of the database system.
TCL (Transaction Control Language): - It is used for the commands related to the transaction of the database.
What do you understand by Query Optimization?
Query optimization is the step that identifies a plan for the evaluation query that has the least estimated cost. It is used when there are multiple algorithms and methods to perform the same task.
What are the benefits of query optimization?
Query Optimization has the following advantages: -
- Output is very fast in this.
- With its help, a lot of Queries can be executed in a very short time.
- It reduces time and space complexity.
What do you understand by Data Model?
It is used as a conceptual tool for Data Describing, Data Relationships, Data Semantics, and Constraints. These Models are used to describe the relationship between Entities and their Attributes.
Following are some Data Models:-
- Hierarchical data model
- network model
- relational model
- Entity-Relationship model
What do you understand by Relation Schema and Relation?
A relation Schema is a set of some specified attributes. This is also called Table Schema. It defines the name of the table. The relation Schema is known as a blueprint with the help of which we can tell how the Data Tables are organized. There is no data in this blueprint.
On the other hand, a Relation can be defined as a set of Tuples.
What are the disadvantages of a File Processing System?
- inconsistent
- not secure
- data redundancy
- Difficulty in accessing data
- Data isolation
- data integrity
- Concurrent access is not possible
- Limited data sharing
- Atomicity problem
What do you understand by Data Abstraction in DBMS?
Irrelevant data is hidden from users in DBMS through the process of Data Abstraction. Because the database system is made up of complex data structures, so with its help the user can easily interact with the database.
How many levels are there in Data Abstraction?
There are three levels to this: -
Physical Level: - This is the lowest level of data abstraction, this level ensures how the data will be stored.
Logical Level: - This level ensures that whatever data is stored in the database, what is the relationship between them.
View Level: - This level describes the entire part of the database.
What do you understand by Normalization?
When a Relation Schema is analyzed on the basis of its Functional Dependencies, then this process is called normalization. It is used during Redundancy, Insertion, and Deletion. Normalization is a very important process that is used for Data Redundancy, insertion anomaly, updation anomaly, and deletion anomaly.
Its most used forms: -
- First Normal Form (1NF)
- Second Normal Form (2NF)
- Third Normal Form (3NF)
- Boyce & Codd Normal Form (BCNF)
Conclusion
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