Introduction to Database System-WEEK2.pptx

database system introduction

1. Introduction to Database System

2. DATA Data is a raw, unanalyzed, unorganized, unrelated, and an uninterrupted entity It is derived from the Latin word “Datum” which means ‘something given’. There are multiple forms of data such as numbers, letters, set of characters, images and graphics Examples: weights, prices, costs, numbers of items sold, employee names, etc.

3. Example 29061996 Is it A birthday A bank account number A telephone number

4. Information Information is a set of data that is processed in a meaningful way according to the given requirement. Example: The student’s average grade for each class , Survey Reports and Results , Census Report, etc.

5. Example 1

6. Example 2 RED What information we attached to the the red color is information For example: On traffic light it means stop In certain places the red color may mean danger zone

7. Example 1

8. IDENTIFY IF ITS DATA OR INFORMATION An email OPTION A= DATA OPTION B = INFORMATION

9. IDENTIFY IF ITS DATA OR INFORMATION BANK STATEMENT OPTION A= DATA OPTION B = INFORMATION

10. IDENTIFY IF ITS DATA OR INFORMATION YES, NO, YES, NO, NO, YES OPTION A= DATA OPTION B = INFORMATION

11. DATA DICTIONARY The data dictionary contains information of the data stored in the database and is consulted by the DBMS before any manipulation operation on the database. It is an integral part of the database management systems and store meta data

12. METADATA . describes the database structure, sizes of data types constraints, applications, autorization etc., that are used as an integral tool for information resource management

13. DATABASE A database is a collection of information that is organized so that it can be easily accessed, managed and updated. Data is organized into rows, columns and tables, and it is indexed to make it easier to find relevant information. Data gets updated, expanded and deleted as new information is added Fields - It is the smallest unit of the data that has meaning to its users and is also called data item or data element. Name, Address and Telephone number are examples of fields   Records - a collection of logically related fields and each field is possessing a fixed number of bytes and is of fixed data type.   Files - A file is a collection of related records  

14. Components of a Database Data item - It is defined as a distinct piece of information 2. Relationships - It represents a correspondence between various data elements. 3. Constraints - These are the predicates that define correct database states. 4. Schema - It describes the organization of data and relationships within the database.

15. RELATIONSHIP

16. CONSTRAINT

17. Database System Application 1. Banking: all transactions 2. Airlines: reservations, schedules 3. Universities: registration, grades 4. Sales: customers, products, purchases 5. Online retailers: order tracking, customized recommendations 6. Manufacturing: production, inventory, orders, supply chain 7. Human resources: employee records, salaries, tax deductions

18. Traditional File System Versus DataBase Management Systems

19. File Base System each file is independent of other file, and data in different files can be integrated only by writing individual program for each application.

20. DATABASE MANAGEMENT SYSTEM It is a software package designed to interact with end- users, other applications, store and manage databases. A general-purpose DBMS allows the definition, creation, querying, update, and administration of databases.

21. Advantages of Database Systems Disadvantages of Database Systems Controlled redundancy Data consistency Program data independence Sharing of data Enforcement of standards Improved data integrity Improved security Data access is efficient Improved backup and recovery facility Minimal program maintenance Complexity increases Requirement of more disk space Additional cost of hardware Cost of conversion Need of additional and specialized manpower Need for backup and recovery Organizational conflict More installation and management cost  

22. Components of DBMS Data Definition Language (DDL) It allows the users to define the database, specify the data types, data structures and the constraints on the data to be stored in the database   Data Manipulation Language (DML) and Query Language DML allows users to insert, update, delete and retrieve data from the database Software for Controlled Access of Database This software provides the facility of controlled access of the database by the users,concurrency control to allow shared access of the database and a recovery control system to restore the database in case of ardware or software failure.

23. Database System Environment Users- People who interact with the database: Application Programmers. End Users. Data - Data Administrators Software- Lies between the stored data and the users: - DBMS. - Application Software. - User Interface.  Hardware- Physical device on which database resides. e.g.: of database Computers, Disk Drives, Printers, Cables etc.

24. DBMS USERS End Users - use the database system through a menu-oriented application program, where the type and range of response is always displayed on the screen Online Users - These type of users communicate with the database directly through an online terminal or indirectly through an application program and user interface. Application Programmers - These are the professional programmers or software developers who develop the application programs or user interfaces for the end user/naive and online users. Database Administrator - a person who have complete control over database of any enterprise. DBA is responsible for overall performance of database.

25. SCHEMAS, SUBSCHEMA AND INSTANCES

26. SCHEMA A schema is plan of the database that give the names of the entities and attributes and the relationship among them. THREE TYPES OF SCHEMA 1.logical schema is concerned with exploiting the data structures offered by the DBMS so that the schema becomes understandable to the computer. It is important as programs use it to construct applications.   2. physical schema is concerned with the manner in which the conceptual database get represented in the computer as a stored database.   3.View schema: Design of database at view level is called view schema. This generally describes end user interaction with database systems

27. Schema Subschema A subschema is a subset of the schema having the same properties that a schema has. It identifies a subset of areas, sets, records, and data names defined in the database schema available to user sessions. The subschema allows the user to view only that part of the database that is of interest to him. The subschema defines the portion of the database as seen by the application programs and the application programs can have different view of data stored in the database. Instances - The data in the database or a database state .

28. THREE LEVEL ARCHITECTURE OF DATABASE SYSTEMS (DBMS) BY ANSI/SPARC external level - The users’ view of the database. This level describes that part of the database that is relevant to each user. 2. conceptual level - The community view of the database. This level describes what data is stored in the database and the relationships among the data. 3. internal level The physical representation of the database on the computer. This level describes how the data is stored in the database.

29. DATA MODELS A data model is a collection of concepts that can be used to describe the structure of the database including data types, relationships and the constraints that apply on the data

30. Three Categories of Data Model

31. RECORD BASE DATA MODEL represent data by using the record structures

32. Hierarchical Data Model Hierarchical Data Model - organizes records in a tree structure i.e., hierarchy of parent and child records relationships.

33. NETWORK MODEL Network Data Model - The ability of this model to handle many to many (N : N) relations between its records is the main distinguishing feature from the hierarchical model. Thus, this model permits a child record to have more than one parent.

34. Relational Data Model Relational Data Model - represented in the form of tables which is used interchangeably with the word Relation. Each table consists of rows also knowns as tuples

35. Entity Relationship Model (ER-Model) allows the representation of the various constraints as well as their relationships. The properties of these entities are their attributes in the ER diagram and their connections are shown in the form of relationships. 

36. Object Based Data Models These models are used in describing the data at the logical and user view levels. These models allow the users to implicitly specify the constraints in the data

37. Object Oriented Model Object oriented data model is also based on using real life scenarios. In this model, the scenarios are represented as objects. The objects with similar functionalities are grouped together and linked to different other objects. used for multimedia applications as well as data with complex relationships.

38. Semantic Data Model used to express greater interdependencies among entities of interest. This class of data models are influenced by the work done by artificial intelligence researchers.

39. Functional Data Model The functional data model describes those aspects of a system concerned with transformation of values-functions, mappings, constraints and functional dependencies

40. Physical Data Models These models provide the concepts that describes the details of how the data is stored in the computer along with their record structures, access paths and ordering. Only specialized or professional users can use these models

41. Two types of Physical Data Model Unifying Model. Frame Memory Model

42. CATEGORIES OF DATABASE SYSTEMS According to the Number of Users According to the Type of Use According to Database Site Locations

43. According to the Number of Users Single-user database systems - In a single user database system, the database reside on a PC–on the hard disk. All the applications run on the same PC and directly access the database.   b. Multiuser database systems - many PC’s are connected through a Local Area Network (LAN) and a file server stores a copy of the database files.

44. According to the Type of Use Production or Transactional Database Systems – used for management of supply chain and for tracking production of items in factories, inventories of items in warehouses/stores and orders for items. b. Decision Support Database Systems - an interactive, computer-based systems that aid users in judgement and choice activities   c. Data Warehouses - designed specifically to meet the transaction processing systems. It can be loosely defined as any centralized data repository which can be queried for business benefit.

45. According to Database Site Locations Centralized database systems - consists of a single processor together with its associated data storage devices and other peripherals. Database files resides on a personal computer (small enterprise) or on a mainframe computer b. Parallel database systems - used in the applications that have to query extremely large databases or have to process an extremely large number of transactions per second c. Distributed database systems - the data is spread across a variety of different databases   d. Client/Server database systems - In client/server technology, there is a server which acts as a whole data base management system and some clients or personal computers which are connected with server through a network interface.