Introduction to Database Systems

  • Describing some common uses of database systems
  • Describing how to handle data
  • Describing Database systems architecture
  • Describing the relational model
  • Describing the database systems development lifecycle






How to handle data ?

Limitations of File-Based Approach

Separation and isolation of data
  • Each program maintains its own set of data.
  • Users of one program may be unaware of potentially useful data held by other programs.
Duplication of data
  • Same data is held by different programs.
  • Wasted space and potentially different values and/or different formats for the same item.
Limitations of File-Based Approach

Data dependence
  • File structure is defined in the program code.
Incompatible file formats
  • Programs are written in different languages, and so cannot easily access each other’s files.
Fixed Queries/Proliferation of application programs
  • Programs are written to satisfy particular functions.
  • Any new requirement needs a new program.