DBMS
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Introduction to Database Management Systems (DBMS), Exercises of Database Management Systems (DBMS)
An overview of database management systems (dbms), including the definition of a database, the purpose of a dbms, and the key advantages of using a dbms. It covers the concepts of data abstraction, data independence, data definition language (ddl), data manipulation language (dml), and the different types of database users. The document also outlines the architecture of a database system, including the various components and their functions. Additionally, it introduces fundamental database terminology such as metadata, data dictionary, and data warehouse. This information would be useful for students studying database systems, particularly in the context of computer science, information technology, or related fields.
Typology: Exercises
2023/2024
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DBMS
Subject Details
BE (CE/IT) Semester III
Subject Code: CT306-N
Subject Title: Database Management Systems
Part - II (Data Models)
Entity-relationship model
Relational and object oriented data models
Integrity constraints
Data manipulation operations.
1. What is Database and DBMS?
● A database is an organized collection of data, so that it can be easily accessed and managed. ● You can organize data into tables, rows, columns, and index it to make it easier to find relevant information. ● The main purpose of the database is to operate a large amount of information by storing, retrieving, and managing data. ● There are many databases available like MySQL, Sybase, Oracle, MongoDB, Informix, PostgreSQL, SQL Server, etc. ● A Database Management System (DBMS) is software designed to store, retrieve, define, and manage data in a database. ● A database system is a collection of interrelated data and a set of programs that allow users to access and modify these data.
❖ Airlines: reservations, schedules
❖ Telecommunication: records of calls, texts, and data usage, generating monthly
bills, maintaining balances on prepaid calling cards
❖ Web-based services
- Online retailers: order tracking, customized recommendations
- Online advertisements
❖ Document databases
❖ Navigation systems: For maintaining the locations of various places of interest
along with the exact routes of roads, train systems, buses, etc.
2.1 Advantages of DBMS
Remove data inconsistency
Civil
Electrical Mechanical
Computer
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Prof. Korth
Ahmeda bad 1234 PPS
Emp_Name Address Mobile Subject
Prof. Korth
Ahmeda bad 1234 PPS
Emp_Name Address Mobile Subject
Prof. Korth Ahmeda bad
1234 PPS
Emp_Name Address Mobile Subject
Prof. Korth Ahmeda bad
1234 PPS
Same data having Database management different state (values) system can keep data in consistent state. Mobile no is changed
Data isolation
Data are scattered in various files.
Files may be in different formats.
Difficult to retrieve the appropriate data.
Emp_Name Address Mobile Subject
Prof. Korth Ahmedabad 1234 PPS
Emp_Name Post Salary Load Prof. Korth Lecturer 50,000 15
Emp_Name Teaching Knowledge Rating Prof. Korth Good Excellent 9
File - 2
File - 3
File - 1
DBMS allow us to access (retrieve) appropriate data easily.
Data isolation is a property that determines when and how
changes made by one operation become visible to other
concurrent users and systems.
This issue occurs in a concurrency situation.
Allow to implement integrity constraints
Emp_Name Address Mobile_No Subject
Prof. Korth Ahmedabad 9876543210 PPS
Student_Name Branch Backlog SPI
Hitesh
Ahmeda bad 0 8.
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Should be between 0 to 10
DBMS allows us to implement such business rules in our database..
Sharing of data among multiple users
Civil
Electrical Mechanical
Computer
Emp_Name Address Mobile Subject
Prof. Korth
Ahmeda bad 1234 PPS
Emp_Name Address Mobile Subject
Prof. Korth
Ahmeda bad 1234 PPS
Emp_Name Address Mobile Subject
Prof. Korth Ahmeda bad
1234 PPS
Emp_Name Address Mobile Subject
Prof. Korth Ahmeda bad
1234 PPS
Database management system allows more than one user to access same data simultaneously.
Want to access
Want to access
Providing backup and recovery services
Provides facilities to backup and restore the database in case of failure.
Advantages of DBMS (Summary)
Reduce data redundancy (duplication)
Avoids unnecessary duplication of data by storing data centrally.
Remove data inconsistency
By eliminating redundancy , data inconsistency can be removed.
Data isolation
A user can easily retrieve proper data as per his/her requirement.
Guaranteed atomicity
Either transaction executes 0% or 100%.
3. View of Data
❖ A major purpose of a database system is to provide users with an abstract view of the data. ★ Data models ● A collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints. ★ Data abstraction ● Hide the complexity of data structures to represent data in the database from users through several levels of data abstraction.
3.1 Level of Abstraction / Data Abstraction
● Physical level : Describes how a record (e.g., instructor) is stored. Lowest level of abstraction. Also called as the Internal Level. ● Logical level : Describes data stored in database, and the relationships among the data. Also called as the Conceptual Level. Create table Query. type instructor = record ID : string; name : string; dept_name : string; salary : integer; end ; ● View level : application programs hide details of data types. Views can also hide information (such as an employee’s salary) for security purposes. User’s Level or External Level.