Chapter 1: Databases and Database Users PDF

CHAPTER 1 Databases and Database Users 1 Database Systems, 8th Edition  OUTLINE Basic Definitions Typical DBMS Functionality Role and Advantages of the DBMS Example of a Database (UNIVERSITY) Main Characteristics of the Database Ap...

CHAPTER 1 Databases and Database Users 1 Database Systems, 8th Edition  OUTLINE Basic Definitions Typical DBMS Functionality Role and Advantages of the DBMS Example of a Database (UNIVERSITY) Main Characteristics of the Database Approach Types of Databases Why Database Design is Important Database Systems 2 Database Systems, 8th Edition  BASIC DEFINITIONS Database: A collection of related data. Data: Known facts that can be recorded. Mini-world: Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university. Database Management System (DBMS): A software package/ system to facilitate the creation and maintenance of a computerized database. Database System: The DBMS software together with the data itself. Sometimes, the applications are also included. 3 Database Systems, 8th Edition BASIC DEFINITIONS (CONT'D.) Meta-data Database definition or descriptive information Stored by the DBMS in the form of a database catalog or dictionary Manipulating a database Retrieval: Querying, generating reports Modification: Insertions, deletions and updates to its content Accessing the database through Web applications Generate reports BASIC DEFINITIONS (CONT'D.) Sharing a database Allow multiple users and programs to access the database at same time Application program Accesses database by sending queries to DBMS Query Causes some data to be retrieved BASIC DEFINITIONS (CONT'D.) Transaction May cause some data to be read and some data to be written into the database Protection includes: System protection Security protection Maintain the database system Allow the system to evolve as requirements change over time  IMPACT OF DATABASES AND DATABASE TECHNOLOGY Businesses: Banking, Insurance, Retail, Transportation, Healthcare, Manufacturing Service Industries: Financial, Real-estate, Legal, Electronic Commerce, Small businesses Education : Resources for content and Delivery More recently: Social Networks, Environmental and Scientific Applications, Medicine and Genetics Personalized Applications: based on smart mobile devices 7 Database Systems, 8th Edition  SIMPLIFIED DATABASE SYSTEM ENVIRONMENT 8 Database Systems, 8th Edition  TYPICAL DBMS FUNCTIONALITY Define a particular database in terms of its data types, structures, and constraints Construct or Load the initial database contents on a secondary storage medium Manipulating the database: Retrieval: Querying, generating reports Modification: Insertions, deletions and updates to its content Accessing the database through Web applications 9 Database Systems, 8th Edition  ADDITIONAL DBMS FUNCTIONALITY DBMS may additionally provide: Protection or Security measures to prevent unauthorized access Presentation and Visualization of data Maintenance of the database and associated programs over the lifetime of the database application 10 Database Systems, 8th Edition  ROLE AND ADVANTAGES OF THE DBMS DBMS is the intermediary between the user and the database Database structure stored as file collection Access database through the DBMS DBMS enables data to be shared 11 Database Systems, 8th Edition  ROLE AND ADVANTAGES OF THE DBMS (CONTINUED) Advantages of a DBMS: Improved data sharing Improved data security Better data integration (wider access to well-managed data) Minimized data inconsistency Improved data access (produce quick answers to ad hoc queries) Improved decision making (generate better quality information) 12 Database Systems, 8th Edition 13 Database Systems, 8th Edition  EXAMPLE OF A DATABASE (WITH A CONCEPTUAL DATA MODEL) Mini-world for the example: Part of a UNIVERSITY environment. Some mini-world entities: STUDENTs COURSEs SECTIONs (of COURSEs) (academic) DEPARTMENTs INSTRUCTORs 14 Database Systems, 8th Edition  EXAMPLE OF A DATABASE (WITH A CONCEPTUAL DATA MODEL) Some mini-world relationships: SECTIONs are of specific COURSEs STUDENTs take SECTIONs COURSEs have prerequisite COURSEs INSTRUCTORs teach SECTIONs COURSEs are offered by DEPARTMENTs STUDENTs major in DEPARTMENTs Note: The above entities and relationships are typically expressed in a conceptual data model, such as the ENTITY-RELATIONSHIP data model (see Chapters 3, 4) 15 Database Systems, 8th Edition  EXAMPLE OF A SIMPLE DATABASE 16 Database Systems, 8th Edition  MAIN CHARACTERISTICS OF THE DATABASE APPROACH Self-describing nature of a database system: A DBMS catalog stores the description of a particular database (e.g. data structures, types, and constraints) The description is called meta-data*. This allows the DBMS software to work with different database applications. Insulation between programs and data: Called program-data independence. Allows changing data structures and storage organization without having to change the DBMS access programs. ----------------------------------------------------------------------------- 17 Database Systems, 8th Edition  EXAMPLE OF A SIMPLIFIED DATABASE CATALOG 18 Database Systems, 8th Edition  MAIN CHARACTERISTICS OF THE DATABASE APPROACH (CONTINUED) Data Abstraction: A data model is used to hide storage details and present the users with a conceptual view of the database. Programs refer to the data model constructs rather than data storage details Support of multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user. 19 Database Systems, 8th Edition  MAIN CHARACTERISTICS OF THE DATABASE APPROACH (CONTINUED) Sharing of data and multi-user transaction processing: Allowing a set of concurrent users to retrieve from and to update the database. Concurrency control within the DBMS guarantees that each transaction is correctly executed or aborted Recovery subsystem ensures each completed transaction has its effect permanently recorded in the database OLTP (Online Transaction Processing) is a major part of database applications. This allows hundreds of concurrent transactions to execute per second. 20 Database Systems, 8th Edition  TYPES OF DATABASES Databases can be classified according to: Number of users Database location(s) Expected type and scope of use Single-user database supports only one user at a time Desktop database – single-user, runs on PC Multiuser database supports multiple users at the same time Workgroup database supports a small number Enterprise database supports a large number 21 Database Systems, 8th Edition  TYPES OF DATABASES (CONTINUED) Centralized database: data located at a single site Distributed database: data distributed across several different sites Operational database: supports a company’s day-to-day operations Transactional or production database Data warehouse: stores data used for strategic decisions (store current and historical data and are used for creating reports) 22 Database Systems, 8th Edition  TYPES OF DATABASES (CONTINUED) Unstructured data exist in their original state Structured data result from formatting Structure applied based on type of processing to be performed Semistructured data It is structured data, but it is not organized in a rational model. A lot of data found on the Web can be described as semi-structured 23 Database Systems, 8th Edition  WHY DATABASE DESIGN IS IMPORTANT Database design focuses on design of database structure used for end-user data Well-designed database: Facilitates data management Generates accurate and valuable information Poorly designed database: Causes difficult-to-trace errors 24 Database Systems, 8th Edition  DATABASE SYSTEMS Database system consists of logically related data stored in a single logical data repository May be physically distributed among multiple storage facilities DBMS eliminates most of file system’s problems 25 Database Systems, 8th Edition 26 Database Systems, 8th Edition  THE DATABASE SYSTEM ENVIRONMENT Database system: defines and regulates the collection, storage, management, use of data Five major parts of a database system: Hardware Software People Procedures Data 27 Database Systems, 8th Edition  THE DATABASE SYSTEM ENVIRONMENT (CONTINUED) Hardware: all the system’s physical devices Software: three types of software required: Operating system software DBMS software Application programs and utility software People: all users of the database system: System and database administrators Database designers Systems analysts and programmers End users 28 Database Systems, 8th Edition  THE DATABASE SYSTEM ENVIRONMENT (CONTINUED) Procedures: instructions and rules that govern the design and use of the database system Data: the collection of facts stored in the database Database technology already in use affects selection of a database system 29 Database Systems, 8th Edition DATABASE USERS Users may be divided into Those who actually use and control the database content, and those who design, develop and maintain database applications (called “Actors on the Scene”), and Those who design and develop the DBMS software and related tools, and the computer systems operators (called “Workers Behind the Scene”). Slide 1- 30 ACTORS ON THE SCENE Database administrators (DBA) are responsible for: Authorizing access to the database Coordinating and monitoring its use Acquiring software and hardware resources Database designers are responsible for: Identifying the data to be stored Choosing appropriate structures to represent and store this data CATEGORIES OF END-USERS Actors on the scene (continued) End-users: They use the data for queries, reports and some of them update the database content. End-users can be categorized into: Casual: access database occasionally when needed Naïve or Parametric: they make up a large section of the end- user population. They use previously well-defined functions in the form of “canned transactions” against the database. Examples are bank-tellers or reservation clerks who do this activity for an entire shift of operations. Slide 1- 32 CATEGORIES OF END-USERS (CONTINUED) Sophisticated: These include business analysts, scientists, engineers, others thoroughly familiar with the system capabilities. Many use tools in the form of software packages that work closely with the stored database. Stand-alone: Mostly maintain personal databases using ready-to-use packaged applications. An example is a tax program user that creates its own internal database. Another example is a user that maintains an address book Slide 1- 33 ACTORS ON THE SCENE (CONT'D.) System analysts Determine requirements of end users Application programmers Implement these specifications as programs WORKERS BEHIND THE SCENE DBMS system designers and implementers Design and implement the DBMS modules and interfaces as a software package Tool developers Design and implement tools Operators and maintenance personnel Responsible for running and maintenance of hardware and software environment for database system