Copyright (c) 2014 Pearson Education, Inc. Introduction to DBMS.

Copyright (c) 2014 Pearson Education, Inc. Introduction to DBMS Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Data - facts that are recorded and can be accessed Data formats text, numbers, graphics, audio/video recordings and more Data is recorded and kept because it is considered to be of use to an intended user Information - refers to the data that is accessed by a user for some particular purpose Typically, getting the needed information from a collection of data requires performing an activity, such as searching through, processing, or manipulating the data in some form or fashion Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 2 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Metadata - data that describes the structure and the properties of the data Metadata is essential for the proper understanding and use of the data Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 3 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Data without metadata - example Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 4 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Data with metadata - example Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 5 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY: File types Sequential Files. (Data Records are arranged sequentially, direct access is not allowed, to access a specific record all the previous records should be scanned first). Relative Files. (each record has a key field number attached to it, storage location is driven from this key, direct access is available, key field should be of consecutive numbers to apply direct access) Indexed Files. (Explain and provide an exaple ) (Indices act as pointers, direct & sequential access methods are available) Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 6 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY: disadvantages of file system Record Duplications. Program-data dependence. Query Language is not available. Recovery mechanism is poor. Very Low level of security. Concurrency control among multiple users is not available. Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 7 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Database - structured collection of related data stored on a computer medium Organizes the data in a way that facilitates efficient access to the information captured in the data Database metadata represents the structure of the database Database content that is not the data itself (data about the data) Contains: o Names of data structures o Data types o Data descriptions o Other information describing the characteristics of the data Juki, Vrbsky, Nestorov Database Systems 8Chapter 1 Slide 8 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Database management system (DBMS) - software used for: Creation of databases Insertion, storage, retrieval, update, and deletion of the data in the database Maintenance of databases DBMS components: Data Definition language:- allow users to define each data element and create databases Data Manipulation Language:- allows accessing and modifying data in the Database. E.g. SQL. Data Control Language:- Control Access to the Database Juki, Vrbsky, Nestorov Database Systems 9Chapter 1 Slide 9 Copyright (c) 2014 Pearson Education, Inc. DBMS ARCHITECTURE (MODELS) Models (1) Levels or views of the Database o Conceptual, logical, physical (2) DBMS types o Relational, Hierarchic, Network, Object-Oriented, Object-Relational 10 Copyright (c) 2014 Pearson Education, Inc. DBMS ARCHITECTURE (MODELS) Defines the ways in which the data can be viewed. (Three General levels):- 1. Internal View (Physical View) :- The way the data is stored in the storage media. (Specified by the DBA) 2. Conceptual View (Logic View):- Describes the structure and constraints for the whole database. (Specified and used by the programmers). 3. External View (Sub-Scheme):- The view of the database as seen by the end user. Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 11 Copyright (c) 2014 Pearson Education, Inc. MODELS (1) Conceptual Model Logical Model External Model Conceptual requirements Conceptual requirements Conceptual requirements Conceptual requirements Application 1 Application 2Application 3Application 4 Application 2 Application 3 Application 4 External Model External Model External Model Internal Model 12 Copyright (c) 2014 Pearson Education, Inc. DATA MODELS(2): HISTORY Hierarchical Model (1960s and 1970s) Similar to data structures in programming languages. Books (id, title) PublisherSubjects Authors (first, last) 13 Copyright (c) 2014 Pearson Education, Inc. DATA MODELS(2): HISTORY Network Model (1970s) Provides for single entries of data and navigational links through chains of data. SubjectsBooks Authors Publishers 14 Copyright (c) 2014 Pearson Education, Inc. DATA MODELS(2): HISTORY Relational Model (1980s) Provides a conceptually simple model for data as relations (typically considered tables) with all data visible. 15 Copyright (c) 2014 Pearson Education, Inc. DATA MODELS(2): HISTORY Object Oriented Data Model (1990s) Encapsulates data and operations as Objects Employee Salaried Employee Consultant Hourly Employee 16 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Typical database system architecture Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 17 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Front-end applications - provide a mechanism for easy interaction between the users and the DBMS End-users (business-users) - users using a database system to support their tasks and processes Indirect interaction - end-user communicating with the database through front-end applications Direct interaction - end-user communicating with the database directly through DBMS Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 18 Copyright (c) 2014 Pearson Education, Inc. INITIAL TERMINOLOGY Typical database system architecture Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 19 Copyright (c) 2014 Pearson Education, Inc. ADVANTAGES OF DATABASE Avoiding Inconsistency. Data is stored in one place (Centralized). Sharing of database. Many applications could share the same data High level of security. Any user can access the data only if he has the authority to do that. Data Integrity. (It means to check that the inserted data is correct) Data Independence. Data is not designed for a specific program, it can be used by more than one application Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 20 Copyright (c) 2014 Pearson Education, Inc. STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 21 Copyright (c) 2014 Pearson Education, Inc. Requirements collection, definition, and visualization - results in the requirements specifying which data the future database system will hold and in what fashion, and what the capabilities and functionalities of the database system will be The collected requirements should be clearly defined and stated in a written document, and then visualized Juki, Vrbsky, Nestorov Database Systems STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Chapter 1 Slide 22 Copyright (c) 2014 Pearson Education, Inc. Requirements collection, definition, and visualization Conceptual database model a visualization of requirements by using a conceptual data modeling technique (such as entity-relationship [ER] modeling) Juki, Vrbsky, Nestorov Database Systems STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Chapter 1 Slide 23 Copyright (c) 2014 Pearson Education, Inc. STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Database modeling (logical database modeling ) - creation of the database model that is implementable by the DBMS software Logical database modeling follows conceptual database modeling Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 24 Copyright (c) 2014 Pearson Education, Inc. STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Database implementation - using a DBMS to implement the database model as an actual database Most modern databases are implemented using a relational DBMS (RDBMS) software Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 25 Copyright (c) 2014 Pearson Education, Inc. STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Developing front-end applications - designing and creating applications for indirect use by the end-users Front-end applications are based on the database model and the requirements specifying the front-end functionalities Front-end applications contain interfaces (such as forms and reports) accessible via a navigation mechanism (such as a menu) Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 26 Copyright (c) 2014 Pearson Education, Inc. STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Database deployment - releasing the database system for use by the end users Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 27 Copyright (c) 2014 Pearson Education, Inc. STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Database use - the insertion, modification, deletion and retrieval of the data in the database system Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 28 Copyright (c) 2014 Pearson Education, Inc. STEPS IN THE DEVELOPMENT OF DATABASE SYSTEMS Database administration and maintenance - performing activities that support the database end user, including dealing with technical issues, such as: Providing security for the information contained in the database Ensuring sufficient hard-drive space for the database content Implementing the backup and recovery procedures Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 29 Copyright (c) 2014 Pearson Education, Inc. THE NEXT VERSION OF THE DATABASE The new version of the database follows the same development steps as the initial version Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 30 Copyright (c) 2014 Pearson Education, Inc. DATABASE SCOPE Databases can vary in their scope from small single-user (personal) databases to large enterprise databases that can be used by thousands of end-users Regardless of their scope, all databases go through the same fundamental development steps (requirements, modeling, implementation, deployment, use, etc.) Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 31 Copyright (c) 2014 Pearson Education, Inc. PEOPLE INVOLVED WITH DATABASE SYSTEMS Database analysts, designers, and developers Database analysts - involved in the requirements collection, definition, and visualization stage Database designers (a.k.a. database modelers or architects) - involved in the database modeling stage Database developers in charge of implementing the database model as a functioning database using the DBMS software Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 32 Copyright (c) 2014 Pearson Education, Inc. PEOPLE INVOLVED WITH DATABASE SYSTEMS Front-end applications analysts and developers Front-end application analysts - in charge of collecting and defining requirements for front-end applications Front-end applications developers - in charge of creating the front-end applications Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 33 Copyright (c) 2014 Pearson Education, Inc. PEOPLE INVOLVED WITH DATABASE SYSTEMS Database administrators (DBAs) - perform the tasks related to the maintenance and administration of a database system Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 34 Copyright (c) 2014 Pearson Education, Inc. PEOPLE INVOLVED WITH DATABASE SYSTEMS Database end users - use a database system to support their work- or life-related tasks and processes Users differ in: o Level of technical sophistication o Amount of data that they need o Frequency with which they access the database system Juki, Vrbsky, Nestorov Database Systems Chapter 1 Slide 35