Introduction to Database AIT632 Chapter 1 Sungchul Hong

Database System The most important development in the field of software engineering. Database serve as the foundation for considerable progress in the basic science fields ranging from computing to biology.

Introduction Database –A collection of related data. DBMS (Database Management System) –The software that manages and controls access to the database. Database application –A program that interacts with the database at some point in its execution.

Examples of Databases Supermarket –Inventory –Customer service Credit card Booking a ticket at the travel agents Using the local library University ??

Geographical Information System

Staff staffNofNamelNamepositionsexDOBsalarybranchNo SL21JohnWhiteManagerMOct/1/ B005 SG37AnnBeechAssistantFNov/10/ B003 SG14DavidFordSupervisorMMar/24/ B003 SA9MaryHoweAssistantF19/Feb/709000B007 SG5SusanBrandManagerFJun/3/ B003 SL41JulieLeeAssistantFJun/13/659000B005 SELECT staffNo, fName, lName, position, salary FROM Staff WHERE salary > 10000; Table Query Language

Relational Database Tables

ERD

File based system v.s. DBMS File based system Database system

Traditional File-Based Systems Each program defines and manages its own data. Separation and isolation of data Duplication of data Data dependence Incompatibility of files Fixed queries of application program

Database Approach A shared collection of logically related data, and a description of this data, designed to meet the information needs of an organization. System catalog (data dictionary) Program-data independence.

File-Based System Sales Files Data entry & report File handling routines File definition

The Database Management System (DBMS) A software system that enables users to define, create, maintain, and control access to the database. Data Definition Language(DDL) Data Manipulation Language (DML) –Structured Query Language (SQL) Views –Level of security, customization, provide consistent structure

Components of the DBMS Environment Hardware –Client-server architecture –Backend, front end Software –DBMS, application programs, SQL Data –Operational data, meta data Procedure –Instructions and rules People

Roles in the Database Environment Data Administrator (DA) –Responsible for the management of the data resource including database planning, development and maintenance of standards, policies, and procedures, and conceptual/logical database design. Database Administrator (DBA)-more technical –Responsible for the physical realization of the database, including physical database design and implementation, security and integrity of the application users.

Roles in the Database Environment (2) Database Designer –Logical database designer Identifying the data, relationship between the data, and the constraints on the data. Business rules. –Physical database designer Mapping the logical database design into a set of tables and integrity constraints. Selecting specific storage structures Designing security measures required on the data

Roles in the Database Environment (3) Application Developer –Provide the required functionality for the end- users. End-Users –Naïve users –Sophisticated users.

Data Redundancy

Typical DBMS Functionality Define a database : in terms of data types, structures and constraints Construct or Load the Database on a secondary storage medium Manipulating the database : querying, generating reports, insertions, deletions and modifications to its content Concurrent Processing and Sharing by a set of users and programs – yet, keeping all data valid and consistent

Typical DBMS Functionality Other features: –Protection or Security measures to prevent unauthorized access –“Active” processing to take internal actions on data –Presentation and Visualization of data

Advantages of DBMS Class

Advantages of DBMS (1/2) Control of data redundancy Data consistency More information from the same amount of data Sharing of data Improved data integrity Improved security Enforcement of standards

Advantages of DBMS (2/2) Economy of scale Balance of confliction requirements Improved data accessibility and responsiveness Increased productivity Improved maintenance through data independence Increased concurrency Improved backup and recovery services

Extending Database Capabilities New functionality is being added to DBMSs in the following areas: –Scientific Applications –Image Storage and Management –Audio and Video data management –Data Mining –Spatial data management –Time Series and Historical Data Management The above gives rise to new research and development in incorporating new data types, complex data structures, new operations and storage and indexing schemes in database systems.

Database Disadvantage Class

Disadvantages of DBMS Complexity Size Cost of DBMS Additional hardware costs Cost of conversion Performance Higher impact of a failure

When not to use a DBMS Main inhibitors (costs) of using a DBMS: –High initial investment and possible need for additional hardware. –Overhead for providing generality, security, concurrency control, recovery, and integrity functions. When a DBMS may be unnecessary: –If the database and applications are simple, well defined, and not expected to change. –If there are stringent real-time requirements that may not be met because of DBMS overhead. –If access to data by multiple users is not required.

History of DBMS Apollo moon-landing project (1960s) –GUAM (Generalized Update Access Method) –Hierarchical structure IMS (Information Management System) (mid 1960s) –Serial storage –device (Tape recorder) IDS (Integrated Data Store) (mid 1960s) –Network DBMS CODASYL (Conference on Data Systems Languages)

History of DBMS DBTG (Data Base Task Group) – 1967 Relational Model – E. F. Codd, 1970 –R –SQL –DB2, SQL/DS, Oracle INGRES II, Informix, Access, FoxPro, Paradox, Interbase, and R:Base ER model – Chen, 1979 –Semantic data modeling Object-Oriented DBMS, Object-Relational DBMS