Chapter-1_091703.pptx

CHAPTER 1 INTRODUCTION ON DATABASE JOSEPHINE T. CRUZ  Objectives At the end of this lesson you will be able to: 1. Differentiate Data and Information 2. Explain Database and Database Management 3. Differentiate different database models  Da...

CHAPTER 1 INTRODUCTION ON DATABASE JOSEPHINE T. CRUZ  Objectives At the end of this lesson you will be able to: 1. Differentiate Data and Information 2. Explain Database and Database Management 3. Differentiate different database models  Data and Information  Data are the raw (unorganized) facts about things Raw data - Not yet been processed to reveal the meaning  Information are Produced by processing data Should be accurate, relevant, and timely to enable good decision making  What is Database?  Database is a collection of related data. E.g. Address book  A database is a well organized, logically related and shared collection of data that is designed to meet the information needs of various users in an organization.  The database is an integrated collection of facts about an organization.  The database is used as a central data source for other applications  What is DBMS? Database Management System (DBMS)  Collection of programs  Manages database structure  Controls access to data store in the database  Role of DBMS Intermediary between the user and the database Enables data to be shared Presents the end user with an integrated view of the data Receives and translates application requests into operations required to fulfill the requests Hides database’s internal complexity from the application programs and users  File System Data management passes through the different levels of development. These levels could best be described by categorizing the levels into three levels of development.  The major three levels are; 1. Manual Approach 2. Traditional File Based Approach 3. Database Approach  Manual Approach In this approach, data storage and retrieval follows the primitive and traditional way of information handling where cards and paper are used for the purpose performed using human labor.  Each of the files containing various kinds of information is labeled and stored in one or more cabinets.  The cabinets could be kept in safe places for security purpose based on the sensitivity of the information contained in it.  Insertion and retrieval is done by searching first for the right cabinet then for the right file then the information  Manual Approach Limitations of the Manual approach: Prone to error Difficult to update, retrieve, integrate You have the data but it is difficult to compile the information Limited to small size information Cross referencing is difficult  File-Based Approach File based systems were an early attempt to computerize the manual filing system by use of computer system.  This approach is the decentralized computerized data handling method.  Every application program that provides service to end users define and manage its own data  File, in traditional file based approach, is a collection of records which contains logically related data.  File-Based Approach Limitations of the File-Based approach: Data Redundancy (Duplication of data) Separation or Isolation of Data: Available information in one application may not be known. Limited data sharing Lengthy development and maintenance time Data dependency on the application Incompatible file formats (Lack of Data Sharing and Availability) Data Inconsistency and confusion Poor Security and administration  Database Approach A Database Approach is shared collection of logically related data, designed to meet the information needs of an organization. – Shared collection – can be used simultaneously by many departments and users. – Logically related - comprises the important objects and the relationships between these objects. – Description of the data – the system catalog (data dictionary or meta-data) provides description of data to enable data independence (program–data independence).  Database Approach  Database is a collection of logically related data where these logically related data comprises entities, attributes, relationships, and business rules of an organization's info.  In addition to containing data required by an organization, database also contains a description of the data which called as “Metadata” or “Data Dictionary” or “Data about Data”. Since it is called a self descriptive collection on integrated records.  The purpose of a database is to store information and to allow users to retrieve and update that information on demand.  Database Approach Characteristics of database approach A number of characteristics distinguish the database approach from the traditional approach of programming with files.  Self-Describing Nature of a Database System  Insulation between Programs and Data, and Data Abstraction  Support of Multiple Views of the Data  Sharing of Data and Multiuser Transaction Processing  Database Approach Advantages of Using the DBMS Approach  Controlling Redundancy  Restricting Unauthorized Access  Providing Backup and Recovery  Data Abstraction  Data Independence  Support Multiple view for different Users  Actors on the  Database Administrators: Scene – The DBA is responsible for authorizing access to the database, for coordinating and monitoring its use, and for acquiring software and hardware resources as needed. – The DBA is accountable for problems such as breach of security or poor system response time.  Actors on the  Database Designers: Scene – Database designers are responsible for identifying the data to be stored in the database and for choosing appropriate structures to represent and store this data. – These tasks are mostly undertaken before the database is actually implemented and populated with data. – It is the responsibility of database designers to communicate with all prospective database users, in order to understand their requirements.  Actors on the  End Users: Scene – End users are the people whose jobs require access to the database for querying, updating, and generating reports.  Actors on the Scene  System Analysts and Application Programmers (Software Engineers) – determine the requirements of end users, especially naive and parametric end users, and develop specifications for canned transactions that meet these requirements. – Application programmers implement these specifications as programs; then they test, debug, document, and maintain these canned transactions. – Such analysts and programmers (nowadays called software engineers).  Basic Database  Enterprise Terminologies – an organization : A library, a bank , a university, etc.  Entity – Person, place, thing, or event (property of an entity) – An "object" in the real world that we are interested in: – The object student is an entity  Attribute (Field) – A character or group of characters (alphabetic or numeric), that has a specific meaning. Eg. Name, age, telephone, grade, sex, etc.  Basic Database  Record Terminologies – A logically connected set of one or more Attributes that describe a person, place or thing. (Logically related data)  File – A collection of related records. For example, a file might contain data about customers; or students of a certain department in a university.  Database – Collection of Files  Database Models  Hierarchical data model – Organize data in a tree structure – There is a hierarchy of parent and child – Data modeling to be one-to-many  Network data model – The same as hierarchical, but network model permits the modeling of many-to-many relationship – A child can have more than one parent  Database Models  Relational data model – Stores data in the form of tables – A table is a collection of records – Each table corresponds to an entity – Allows the definition of data and integrity constraints  Object-oriented data model – Faster than relational database model – Applications require less code – Add database functionality to object programming language ! Thank you !