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Introduction to Database Systems Motivation

Introduction to Database Systems Motivation. Irvanizam Zamanhuri, M.Sc Computer Science Study Program Syiah Kuala University Website: http://www.informatika.unsyiah.ac.id Email: irvanizam.zamanhuri@informatika.unsyiah.ac.id. Databases Are Everywhere.

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Introduction to Database Systems Motivation

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  1. Introduction to Database SystemsMotivation Irvanizam Zamanhuri, M.Sc Computer Science Study Program Syiah Kuala University Website: http://www.informatika.unsyiah.ac.id Email: irvanizam.zamanhuri@informatika.unsyiah.ac.id

  2. Databases Are Everywhere • Database = a large (?) collection of related data • Classically, models a real-world organisation (e.g., enterprise, university) • Entities (e.g., students, courses) • Relationships (e.g., “Sergio is taking IDS in 2006/07”) • Changes in the organisation = changes in the database • Examples: • corporate records • banking • airline reservations

  3. Scientific Databases (Examples) • Biology: e.g., DNA sequences of genes, amino-acid sequences of proteins, genes expressed in tissues (up to several Gigabytes) • Astronomy: e.g., location and spectra of astronomic objects (up to several Terabytes) • Physics: e.g., sensor measurements in particle physics experiments (up to several Petabytes)

  4. DB Tendencies • Data are recorded by sensors  DBs grow in size DBs become more widespread • Computers are becoming more powerful DB Management Systems can run on laptops (and soon on phones and chip cards?) • Multimedia data arise everywhere Requirements for larger storage  New query operations

  5. Operations with Databases • Design • Define structure and types of data • Construction • Create data structures of DB, populate DB with data • Manipulation of Data • Insert, delete, update • Query: “Which department pays the highest salary?” • Create reports: “List monthly salaries of employees, organised by department, with average salary and total sum of salaries for each dept”

  6. Structure data types data behaviour Persistence store data on secondary storage Retrieval a declarative query language a procedural database programming language Performance retrieve and store data quickly Data Integrity Sharing concurrency Reliability and resilience Large data volumes An Ideal DB Implementation Should Support:

  7. Database Management System(DBMS) • A DBMS is a software package designed to store and manage databases • A DBMS provides generic functionality (see previous slide) that otherwise would have to be implemented over and over again Reduced application development time • Several brands, e.g., • DB2 (IBM), SQL Server, Access (Microsoft), Oracle Xi (Oracle), MySQL, PostgreSQL (open source)

  8. DatabaseDesigners Application Programmers DatabaseAdministrator (DBA) • End Users • sophisticated • casual • ‘parametric’ or ‘canned’ transactions Database DBMS developers Operators and Maintenance Personnel Tool Developers Database Management System DBMS Actors “on the scences” “behind the scenes”

  9. File System: A Physical Interface Student Year Lists Student Data Admin Course Data Timetable Scheduler Lecturer Data Payroll Cheques

  10. Sharing data:Replication  Redundancy Student Admin Student Data Lab Timetable Course Data Tutorials Lecturer Data Scheduler Teaching Schedule Payroll

  11. Sharing Data and Operations Student Admin Student Data Lab Timetable Tutorials Course Data Scheduler Teaching Lecturer Data Schedule Payroll

  12. DBMS: A Logical Interface Lab University Database Timetable Data Database Teaching Management course Schedule System student lecturer Tutorials Data Dictionary or System Catalog University Database Metadata ?QUERIES

  13. File System Approach • Uncontrolled redundancy • Inconsistent data • Inflexibility • Limited data sharing • Poor enforcement of standards • Low programmer productivity • Excessive program maintenance • Excessive data maintenance

  14. Controlled redundancy consistency of data & integrity constraints Integration of data self-contained represents semantics of application Data and operation sharing multiple interfaces Services & controls security & privacy controls backup & recovery enforcement of standards Flexibility data independence data accessibility reduced program maintenance Ease of application development DBMS Approach

  15. If an application is simple stringent real-time single user static, files are the option of choice DBMS downside: more expensive more complex general In a file system, data is physically accessed and unintegrated In a DBMS, data is logically accessed and integrated: query language data dictionary However.... Summary:

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