Database Management Systems - Management Information System

A DBMS is software that:Acts as an interface between application programs and the data files.Helps to reduce data redundancy and eliminate data inconsistency by allowing a central, shared data source

1. Database Management System Prepared by NIJAZ N Asst. Professor CHMM College for Advanced Studies Varkala

2. Organizing Data in a Traditional File Environment Organize data in fields , records and files. Field - A grouping of characters into a word, a group of words or a complete number ( eg : person’s name or age) is called a field. Record – A group of related fields comprises a record ( eg : student’s name, course taken, date and grade) File - A group of records of the same type ( eg : course file) Difficult to keep track of all the pieces of data. Different functional areas and groups were allowed to develop their own files independently.

3. Problems with File System Data Redundancy Presence of duplicate data in multiple files so that the same data are stored in more than one place or location. Data Inconsistency Same data may have different values. Lack of flexibility Difficult to deliver ad hoc reports or respond to unanticipated information requirements in a timely fashions. Poor Security Little control over data or access of data. Lack of Data Sharing Information cannot flow freely across different functional areas

4. Database Is a collection of data organized. Serve many applications efficiently by Centralizing the data Controlling the redundant data. A single database services multiple application rather than storing data in separate files for each application. E.g.:- A University database through which university applications from the Registrar’s office, the Accounting department, and the Examination department access data

5. DBMS Software that defines a database, stores the data, supports a query language, produces reports, and creates data-entry screens. A DBMS is software that: Acts as an interface between application programs and the data files. Helps to reduce data redundancy and eliminate data inconsistency by allowing a central, shared data source

6. Physical view DBMS Logical View Logical & physical view Data as perceived by end users/business specialists How data are actually organized on physical storage media

7. DBMS – Components/Requirements Formal language used by the programmers to specify the structure/content of the database Contains commands that permit end users to extract data from the database to satisfy information requests Automated/manual file that stores definitions of data elements and data characteristics

8. Database Models /Types

9. Relationship Model Proposed in 1969 by Edgar F. Codd Depicts data logically as many-to-many relationships All data is represented in terms of tuples , grouped into relations Order list of elements

10. Hierarchical Model Organizes data in a tree-like structure Supports one-to-many /parent-child relationships Prevalent in large legacy systems

11. Network Model Depicts data logically as many-to-many relationships Object types are nodes and relationship types are arcs

12. Object Oriented Model Organizes data in a tree-like structure Supports one-to-many parent-child relationships Prevalent in large legacy systems