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Introduction To Databases and DBMS

  • Databases are globally used - air/railway reservation, online auction/shopping etc.
  • Databases are backbone of information age
  • Bigger & better applications are being developed to access and manipulate the stored data
  • To bring down associated costs, following features are desired:
  • support for multiple platforms and specific optimization in a Data Base Management Systems (DBMS)
  • flexible & scalable data sources
  • Database is collection of related data organized and classified in a structured format that is described by metadata (data about data) which defines how data is defined and stored
  • this is required to provide efficient access and maintenance
  • e.g. structuring information in a phonebook - data field, their types, constraints
  • Database is collection of related files of different record types.
  • Yet another definition is: Repository of stored data which is both integrated (I.e. unified with reduced redundancies) and shared. 
  • Data Base Management System (DBMS) record and maintain information (meaningful data).
  • DBMS hides all details of data stored and present to use on desired operation. Some operations include add, modify, delete, create files and data, sorting, math functions, data integrity etc.
USER ------>QUERIES/PL/I, COBOL----->DBMS(SUBPROGRAMS/IINTERRELATED FILES)------>OS------>DATABASE---->HARDWARE