Anshu Joshi_2371050_DBMS.pptxData base management system

Dbms ppt.

1. Introduction to Database Systems By Prof. Sreenivasa Kumar IIT MADARAS

2. COURSE LAYOUT Week 1 : Introduction and part of E/R Model Module Week 2 : ER Model Module Week 3 : Relational Model Module Week 4 : Relational Model Module Week 5 : TRC Module and part of SQL Module Week 6 : SQL Module Week 7 : Indexes Module Week 8 : Indexes Module + Query Processing Module Week 9 : Normal Forms Module Week 10 : Normal Forms Module Week 11 : Transaction Processing Module Week 12 : Transaction Processing Module

3. What Is Data ? Different view points: A sequence of characters stored in computer memory or storage Interpreted sequence of characters stored in computer memory or storage Interpreted set of objects This maybe one of the most profound questions in computer science! It is still open and keep evolving!!

4. Where are databases? You cannot avoid it and it’s everywhere! You can say it actually makes the current society and your life work! Banking/Credit card /Social Security Info… Online shopping/booking…

5. Database Definition A database is a collection of stored operational data used by various applications and/or users by some particular enterprise or by a set of outside authorized applications and authorized users A DataBase Management System (DBMS) is a software system that manages execution of users applications to access and modify database data so that the data security, data integrity, and data reliability is guaranteed for each application and each application is written with an assumption that it is the only application active in the database.

6. Advantages of Databases Persistent Storage – Database not only provides persistent storage but also efficient access to large amounts of data Programming Interface – Database allows users to access and modify data using powerful query language. It provides flexibility in data management Transaction Management – Database supports a concurrent access to the data

7. Pre-Database Era: Stone Age of Data Imagine you want build an online shopping website Maintain products/categories (price, picture, properties, …) Customers accounts File is uninterpreted, unstructured collection of information File operations: delete, catalog, create, rename, open, close, read, write, find, … Access methods: Algorithms to implement operations along with internal file organization Examples: File of Customers, File of Products; Access method: implementation of a set of operations on those files

8. Data Integrity A database constraint is a logical constraint about the data expressed in a logical language. STUDENT.AGE >15 If ( STUDENT.CLASS ==cs43005) then (STUDENT.PRIOR_CLASS ==cs31001) Database is consistent if data at each time satisfies all integrity constraints. Input to any application is a set of consistent data. An application output is a set of consistent data.

9. Database Languages SELECT Chair FROM Faculty, Department WHERE Faculty.name = “Ken Noname” AND Faculty.Dept = Department.Dept Data definition language (DDL) ~ like type definitions in C or C++ Data Manipulation Language (DML) Query (SELECT) UPDATE < relation name > SET <attribute> = < new-value> WHERE <condition> Faculty Name Dept Department Dept Chair SQL

10. Data Definition Language Specification notation for defining the database schema E.g. create table account ( account-number char (10), balance integer ) DDL compiler generates a set of tables stored in a data dictionary Data dictionary contains metadata (i.e., data about data) database schema Data storage and definition language language in which the storage structure and access methods used by the database system are specified Usually an extension of the data definition language

11. Data Administrator Coordinates all the activities of the database system; the database administrator has a good understanding of the enterprise’s information resources and needs. Database administrator's duties include: Schema definition Storage structure and access method definition Schema and physical organization modification Granting user authority to access the database Specifying integrity constraints Acting as liaison with users Monitoring performance and responding to changes in requirements

12. Database Users Naïve – do not know about database too much, invoke application programs that are prepared already Application Programmers – know how to interact with the system but may not know how DBMS is designed Sophisticated users that know advanced use of the system and can use the system and packages on the top of the system DBMS system users – write specialized database applications that do not fit into the traditional data processing framework

13. References A. Silberschatz, H. F. Korth, S Sudarshan, Database System Concepts, 5 th Ed., McGrow Hill, 2005 http://www.db-book.com Hector Garcia-Molina, Jeffrey D. Ullman, Jennifer Widom, Database Systems, The Complete Book, Prentice Hall, 2002 http :// www-db.stanford.edu/~ullman/dscb.html Class notes

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