An Introduction to database system Database Management COP4540, SCS, FIU

Basic Definitions Data: Meaningful facts, text, graphics, images, sound, video segments. Database: An organized collection of logically related data. Information: Data processed to be useful in decision making. Metadata: Data that describes data. Database Management COP4540, SCS, FIU

What is a DataBase system? (DB) It is a logically coherent collection of data with inherent meaning. It represents a miniworld, and should represent the state of that world accurately. It is managed by a database management system (DBMS). Database Management COP4540, SCS, FIU

What is a DataBase Management System? (DBMS) A (large) piece of software which provides an interface between the user or application program and the stored data. A DBMS is developed according to a particular data model. Some example DBMSs are: IMS, DB2, Oracle, Sybase, Informix, SQL Server, Access, FoxPro, O2. Database Management COP4540, SCS, FIU

The functionality of DBMS Manages very large amounts of data. Supports efficient access to very large amounts of data. Supports concurrent access to very large amounts of data. Supports secure, atomic access to very large amounts of data. Database Management COP4540, SCS, FIU

Several basic concepts Data models A data model is a way of representing (part of) the world. The principle current data model are: Hierarchical Network Relational Object-oriented E-R Semantic Database Management COP4540, SCS, FIU

Several basic concepts Database design Design goals Minimize redundancy in order to eliminate the modification anomalies in database. Represent the situation accurately Design Stages Conceptual (product independent) Logical (product specific) Physical / Implementation (product specific) Database Management COP4540, SCS, FIU

Database Development Activities The stages focused in COP4540 Database Management COP4540, SCS, FIU

Conceptual Database Modeling Determine user requirements. Determine business rules. Build conceptual data model outcome is an entity-relationship diagram or similar communication tool. Database Management COP4540, SCS, FIU

Logical Database Design Select logical database model. Map Entity-Relationship Diagrams Normalize data structures. Specify business rules. Database Management COP4540, SCS, FIU

Physical Database Design Select DBMS Select storage devices Determine access methods Design files and indexes Determine database distribution Specify update strategies Database Management COP4540, SCS, FIU

Several basic concepts Schema Logical structure of the data defined by using data definition language (DDL). Queries A “query” is a database lingo for a question about the data. A “query” is composed by using query language (QL) Database Management COP4540, SCS, FIU

The architecture of database system Users / Programmers Application Programs / Queries 1. Software to process queries/programs 2. Software to access stored data Database Management System Stored data Database Management COP4540, SCS, FIU

Components of the Database Environment CASE Tools Repository Database Management System (DBMS) Database Application Programs User Interface Database Administrators (DBA) System Developers End Users Database Management COP4540, SCS, FIU

Evolution of Database Systems Hierarchical and Network (Legacy): Data are modeled as linked records. Relational: Data are modeled as related tables. Object-oriented: Data are organized as linked objects. Object-relational: Integration of relational and object-oriented features. Database Management COP4540, SCS, FIU

RDBMS and SQL RDBMS is a DBMS on the basis of relational model. It is the most popular type of the DBMS. The data is organized as tables called relations Two famous systems: System R at IBM & Ingres at UC Berkeley SQL (Structured Query Language) the most important query language based on relational model. Database Management COP4540, SCS, FIU

RDBMS and SQL SELECT balance Result: FROM Accounts 2846.92 WHERE accountNo = 67890 Result: 2846.92 Database Management COP4540, SCS, FIU

Disadvantages of File Processing Systems Data Dependence Data Redundancy (Duplication of data) Limited Data Sharing Lengthy Development Times Excessive Program Maintenance Database Management COP4540, SCS, FIU

Advantages of Database Approach Program-Data Independence: No need to rewrite programs when data is modified Minimal Data Redundancy Improved Data Consistency Improved Data Sharing Increased Application Development Productivity. Database Management COP4540, SCS, FIU

Advantages of Database Approach Enforcement of Standards Improved Data Quality (Constraints) Better Data Accessibility/Responsiveness Reduced Program Maintenance Security, Backup/Recovery, Concurrency Database Management COP4540, SCS, FIU

Costs and Risks of the Database Approach New, Specialized Personnel Installation Management Cost and Complexity Conversion Costs Organizational Conflict Database Management COP4540, SCS, FIU