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Database Management Systems Chapter 1: Introduction to Databases

Database Management Systems Chapter 1: Introduction to Databases. Instructor: Manuel Penaloza, Ph.D. Manuel.Penaloza@sdsmt.edu. Examples of Database Applications. Common Applications: Store and online purchases Travel booking Web applications Others: Geographic information systems

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Database Management Systems Chapter 1: Introduction to Databases

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  1. Database Management SystemsChapter 1: Introduction to Databases Instructor: Manuel Penaloza, Ph.D. Manuel.Penaloza@sdsmt.edu

  2. Examples of Database Applications • Common Applications: • Store and online purchases • Travel booking • Web applications • Others: • Geographic information systems • Data warehouses • Bioinformatics

  3. File-based Systems • Prior to database systems • Collection of application programs that perform services for the end users (e.g. reports). • Each program defines and manages its own data.

  4. Limitations of File-based Approach • Separation and isolation of data • Each program maintains its own set of data. • Duplication of data • Same data is held by different programs. • Same item w/ different values and/or formats • Data dependence • File structure is defined in the program code • Incompatible (output) file formats and fixed queries • No security, integrity, or recovery • Restricted access through application

  5. Database Approach • Arose because: • Definition of data was embedded in application programs, rather than being stored separately and independently. • No control over access and manipulation of data beyond that imposed by application programs. • Result: • The database and Database Management System (DBMS). • It provides data-program independence

  6. Database • Shared collection of logically related data designed to meet the information needs of an organization. • Data are known facts that can be recorded and have an implicit meaning. • Database Management System (DBMS) • A software system designed to store and manage databases easily and efficiently. • Database application: Program that manipulates a specific database managed by a DBMS. • Database system: It includes the DBMS, database and database application.

  7. Database Management System (DBMS) Database applics File Defn & Data Handling. Database Figure 1.7

  8. 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 (retrieve, access, and update) the database and its metadata (system catalog) • Controlling access to the databases using modules that handle: • Security, integrity, concurrency control, recovery control, database views, query processing

  9. System Catalog • Repository of information (metadata) describing the data in the database. • Typically stores: • Names of authorized users. • Names of data items in the database. • Constraints on each data item. • Data items accessible by a user and the type of access. • Used by some of the DBMS modules. • Allows changing data structures and storage organization without having to change the DBMS access programs.

  10. Roles in the Database Environment • Data Administrator (DA) • Responsible for the enterprise data • Database Administrator (DBA) • Database Designers (Logical and Physical) • Application Programmers • End Users (naive, standalone, and sophisticated) • DBMS Designers and Implementers • Tool developers

  11. Advantages of DBMS • Control of data redundancy • Preserve data consistency • Sharing of data • Improve security • Increase productivity • Support of multiple views of the data • Improve maintenance through data independence • Increase concurrency • Improve backup and recovery services

  12. Disadvantages of DBMS • Complexity • Size • Cost of DBMS • Additional hardware costs • Cost of conversion • Performance • Overhead for providing generality, security, concurrency control, recovery, and integrity functions • Higher impact of a failure

  13. 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. • When no DBMS may suffice: - If the database system is not able to handle the complexity of data because of modeling limitations - If the database users need special operations not supported by the DBMS.

  14. History of Database Systems • First-generation (60’s) • Hierarchical (oldest): Data organized as a tree • IMS (Hierarchical) introduced by IBM • Network (moon landing): Tree replaced by a graph • Second generation (70’s) • Relational: Introduced by Ted Codd (IBM) in 1970 • System R was the first implementation in early 70’s at IBM • Oracle released first commercial RDBMS in 1979 • Third generation (90’s) • Object Relational • Object-Oriented

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