IntroductiontoDBMS

IntroductiontoDBMS - C C ourse ourse 1 1 I I ntroduction to...

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Unformatted text preview: C C ourse ourse 1 1 I I ntroduction to ntroduction to D D BMS BMS Dr. A nis K OUBAA C omputer omputer S cience (CS cience (CS 420 420 ) D D atabase atabase M M anagement anagement S S ystems ystems (DBMS) (DBMS) Table of contents Definition of DBMS Objective of DBMS Database System Applications Purpose of Databases Limitation of the file system based databases View of Data in Databases Data Models Database Languages Database Users and Administrator Definition of DBMS A database management system (DBMS) is a collection of interrelated data (database) and a set of programs to access those data. Objective of DBMS Provide a way for efficient data management storage and retrieval of the information Manage large bodies of information Defining structures for the storage of information Providing the mechanisms for the manipulation of the information Ensure the safety of the information stored Avoid abnormal results when sharing the DB among several users Database System Applications Banking: all transactions Airlines: reservations, schedules Universities: registration, grades, student information Sales: customers, products, purchases Manufacturing: production, inventory, orders, supply chain Human resources: employee records, salaries, tax deductions Telecommunications: keeping record of calls made, generating monthly bills Purpose of Database Systems Limitations of File Systems (1/3) In the early days, database applications were built on top of file systems Data is stored in separate files Data is manipulated by a set of application programs As time goes by, the number of files and application programs increases increasing complexity of database application management Purpose of Database Systems Limitations of File Systems (2/3) Drawbacks of using file systems to store data Data redundancy and inconsistency Redundancy: duplication of information in different files Inconsistency: the various copies of the same data may be different Difficulty in accessing data Need to write a new program to carry out each new task Data isolation multiple files and formats Because data are scattered in various files, and files may be in different formats, writing the appropriate information to retrieve the appropriate data is difficult Integrity problems Data values stored in the database must satisfy certain types of consistency constraints Integrity constraints (e.g. account balance > 0) become part of program code Those constraints are forced by the database system developer Hard to add new constraints or change existing ones Purpose of Database Systems...
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IntroductiontoDBMS - C C ourse ourse 1 1 I I ntroduction to...

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