Overview of DBMS.

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Overview of DBMS.

OVERVIEW OF DBMS

•Data needs of current and possible future applications determined

•Using E-R data modelling conceptual data model found

•Converted to relations if Relational DBMS used

- called logical data model

•Application programmers access subset of logical data model

- called external data model

•Logical model mapped to physical model for storage in disk store

- called internal model

•External data model kept invariant

VARIOUS TERMS USED IN DESCRIBING DBMS

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COMPONENTS OF DBMS

•Data Definition Languages (DDL) to define conceptual, logical and external models

•Data manipulation and query language called Structured Query Language (SQL)

•Features to implement security

•Checkpointing and roll back recovery procedures

•Record of accesses. Audit trail of changes

DATABASE ADMINISTRATOR

Database Administrator’s responsibilities are controlling of data recourse, to ensure integrity, security and privacy, maintenance of data dictionary, coordination of development and maintenance of data base and determining access rights

CHARACTERSTICS OF A GOOD DATA BASE DESIGN

•Satisfy current and future needs of organization

•Cater to unanticipated user requirements in the best possible way

•Expandable with growth and changes in organization

•Easy to change when hardware and software change

•Ensure data security by allowing only authorized persons to access and modify database

REFERENCES

1. Most of the material in this module has been adapted from the book “Analysis and Design of Information Systems”, 2nd Edition, by V.Rajaraman. Chapter 10 Logical Data Base Design, pp.130 to 153. Chapter 12 , Data Base Management Systems, pp. 171 –1719.

2. Good treatment of E-R Modelling and Normalization may be found in the book “Introduction to Systems analysis and Design”, by I.T.Hawryszkiewycz, Prentice Hall of India, 1989.

3. For those interested in detailed study of Data Base Design and DBMS, the following books are standard texts:

1, R.Elmasri and S.B.Navathe, Fundamentals of Data Base Systems, 4th Edition, Pearson Education Asia, New Delhi, 2004.

2. T.Connolly and C.Begg, Dta Base Systems, 3rd Edition, Pearson Education Asia, New Delhi, 2003.

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