Database System Web Database system and web Why

Database System & Web

Database system and web Why to study this subject? Following are some of the benefits Help you in projects Placements Gate

Data is a collection of facts that have some implicit meaning, such as values or measurements. It can be numbers, words, measurements, observations or even just descriptions of things.

DATABASE A collection of related pieces of data: Representing/capturing the information about a enterprise or part of an enterprise. real-world A database is designed, built, populated with data for a specific purpose. It has intended group of users and preconceived application. Activities of the enterprise are supported by the database and continually update the database.

DATABASE Example: University Database Data about students, faculty, courses, laboratories, course registration/enrollment etc. Purpose: To keep an accurate track of the academic activities of the university.

Database cont… Database is an essential component of everyday life. In a day we encounter several applications that consist of interaction with database Applications? Database Applications: Banking: all transactions Airlines: reservations, schedules Universities: registration, grades Sales: customers, products, purchases Manufacturing: production, inventory, orders, supply chain Human resources: employee records, salaries, tax deductions

Data is also stored in excel sheets. Is it different from database?

What is a DBMS? A Database Management System (DBMS) is a software package designed to store and manage databases. Defining: Specifying data types, structures, and constraints of the stored data Example: 0<=CGPA <=10 Constructing: storing the data Manipulating: querying the data

What is a DBMS? Cont… DBMS tasks: Managing large quantity of structured data Efficient retrieval and modification: query processing and optimization Sharing data: multiple users use and manipulate data Controlling the access to data: maintaining the data integrity

Why there is a need of DBMS? What methods were used earlier?

The Characteristics of a DBMS Self Describing nature: DBMS consist of data as well as meta-data (type, constraints) about it Traditional files don’t have any such meta-data, struct etc. were written the application code Insulation between program and data In files, if we change the structure of a files we need to change all the programs using it In database structure is stored in DBMS, hence , we don’t have any such problem

The Characteristics of a DBMS Cont… Support multiple view of data: DBMS allow different user different view. For example, students can see only their marks File system does not have any such support, either a complete file visible or not Sharing data and multiuser transaction: DBMS allow concurrency control File don’t have

Example of relational model Attributes Example of tabular data in the relational model Customer-id customername 192 -83 -7465 Johnson 019 -28 -3746 Smith 192 -83 -7465 Johnson 321 -12 -3123 Jones 019 -28 -3746 Smith customerstreet customercity accountnumber Alma Palo Alto A-101 North Rye A-215 Alma Palo Alto A-201 Main Harrison A-217 North Rye A-201

A Sample Relational Database

A Sample Relational Database • Define: Define structure of this database, for example: customer id is a 9 digit number with ‘-’ in between • Construct: We store data in this such as smith record • Manipulating: querying such as, find account numbers with balance < 500

Roles for people DBA (Database Administrator) Grant / Revoke data access permissions to other users etc DBA Designers Designing the logical schema Creating the structure of the entire database Monitor usage and create necessary index structures to speedup query execution Naive users – invoke one of the permanent application programs that have been written previously E. g. people accessing database over the web, bank tellers, clerical staff Sophisticated users – Complex queries include scientist, engineers

The Advantages of a DBMS Minimal data redundancy. Restricting unauthorized access. Providing persistent storage. Providing multiple user interface Enforcing constraints. Backup and Recovery

Summary DBMS used to maintain, query large datasets. Benefits include recovery from system crashes, concurrent access, quick application development, data integrity and security. Levels of abstraction give data independence. A DBMS typically has a layered architecture.

Text Books: Henry F Korth, Abraham Silberschatz, S. Sudurshan, Database system concepts, 5 th Edition. Ramez Elmasri , Shamkant B. Navathe , Fundamentals of Database Systems, 4 th Edition, Pearson Education. H Garcia-Molina, J D Ullman, and Jennifer Widom, Database Systems-The Complete Book, Pearson Education.