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Databases introduction: what are they?

Databases introduction: what are they?. Hossein Rahmani Slides originally by Dr. Ir. Jos Uiterwijk. Introduction. Lecturer Hossein Rahmani Post-doc researcher in DKE All area of data analysis Databases, Data mining, Graph Mining, Pattern Mining etc Teaching Assistanst:

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Databases introduction: what are they?

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  1. Databases introduction: what are they? Hossein Rahmani Slides originally by Dr. Ir. Jos Uiterwijk

  2. Introduction • Lecturer • Hossein Rahmani • Post-doc researcher in DKE • All area of data analysis • Databases, Data mining, Graph Mining, Pattern Mining etc • Teaching Assistanst: • Bijan Ranjbar Sahraei • PhD researcher in DKE • Databases, Data mining, Computational Social Science Databases lecture 1a

  3. Materials and Clarification • Fundamentals of database system (5th/6th) • Final Grade = • 75% final Exam + 25% Assignments • 1 or 2 assignments • Individually Databases lecture 1a

  4. Schedule Databases lecture 1a

  5. Schedule • Monday (8:30-10:30) • Lectures Sessions • Big Picture of topics • Details, refer to book • Tuesdays • Work group sessions • Group of 3/4/5 • Discuss in Group the assignments • Discuss the final result with Bijan Databases lecture 1a

  6. Databases • Most of our daily activities involve some interaction with Database • Different kinds of databases • Traditional databases • Text and Numeric • Multi-media databases • Images and video streams • Geographical information systems • Maps, weather data • Data warehouses • Extract and analyse useful information to support decision making Databases lecture 1a

  7. Definitions • Database: a collection of coherent data. • Data: facts that can be recorded and that have an implicit meaning. Databases lecture 1a

  8. Properties • Properties of databases: • Represent a specific aspect of the real world (mini world or Universe of Discourse). • Changes in the mini world are reflected in the database. • Data in the database are logically coherent. • A database has a specific goal. Databases lecture 1a

  9. Automated database • Database management system (DBMS) • Generally applicable system for: • Defining a database • Data types, structures, restrictions • Building a database • Storing data on a storage medium • Manipulating a database • Query, update, insert Databases lecture 1a

  10. Databases lecture 1a

  11. Database example Databases lecture 1a

  12. File approach • Use java (or another tool) to create and read binary files or text files • Targeted at a specific situation • Can be very fast and effective for such a situation Databases lecture 1a

  13. File approach • Same data can be stored at multiple spots in the application: cause of discrepancies and errors • Maintenance is difficult: a programmer is needed to change an application • Exchange of data is difficult Databases lecture 1a

  14. Database approach Vs File approach • Self description: a DBMS not only contains data but also a catalogue with data on the data: meta-data Databases lecture 1a

  15. Database approach Vs File approach • Data-abstraction (cf. ADT’s): • When data storage is changed, the application often can remain unchanged • In some DBMS-s also operations on the data can be stored • Conceptual representation of data (data model) Databases lecture 1a

  16. Database approach Vs File approach • Multiple viewpoints • Different users have different roles / perspectives / needs with respect to the data in the database • Everyone has an own “virtual” database: views in DBMS Databases lecture 1a

  17. Two Views Databases lecture 1a

  18. Database approach Vs File approach • Multiple users: • Multiple users access the same data • DBMS provides Concurrency Control • Dealing with simultaneous changes of data • Concept of transactions • One or more database access that should run All or None • Roll-back of large operations that could not be completed (operations should be atomic) Databases lecture 1a

  19. Players at the front • Database administrator • Security/Performance Issues • Database designer • Requirement Engineering • Design Data model • End users • Querying/Updating/Analysing Data • System analysts and programmers • Design and Implement Canned Transations Databases lecture 1a

  20. Players at the background • DMBS designers & programmers • Implement catalog, accessing and buffering data etc • Tool designers • Optional practical packages • Operators and maintenance personnel • Maining of the hardware and software Databases lecture 1a

  21. Advantages DBMS • Reduce redundancy • reduce storage space • simplify updates • prevent errors (inconsistency) • Increase security • User management (passwords / authorization) • Log actions and changes (audit log) • Backup and restore procedures Databases lecture 1a

  22. Advantages DBMS • Persistant storage of objects and data structures (i.e., object-oriented database systems) Databases lecture 1a

  23. Advantages DBMS • Multiple simultaneous user environments • Front-ends • GUI’s • Web access • Application servers / web services • API’s Databases lecture 1a

  24. Advantages DBMS • Store and maintain complex relations between data • Enforce integrity constraints • Simple: Data Type for data item • Complex: Relationship among records from different tables/files Databases lecture 1a

  25. Effects of DBMS • Standardisation possible • Faster development of applications • Flexibility • Up-to-date information available • Scalability Databases lecture 1a

  26. Brief History • Early database systems (up to 1980) • Mixing conceptual relations and physical storage aspects • Hierarchic model and Network model • Only interfaces for programming languages (especially Cobol) • Implemented on large and expensive mainframes Databases lecture 1a

  27. Brief History • Relational databases (since 1980) • Separation of conceptual design and physical storage • Slow at the beginning, now fast because of new indexing methods • At present the most important type, available on all platforms, both commercial and open-source (e.g. MySQL). Databases lecture 1a

  28. Brief History • Object oriented databases (since 1980) • More powerful than relational DBMS, but not a true rival • Internet and E-commerce (since 1995) • Webpages are created by use of databases • XML is a standard for data exchange • XML leads to reintroduction of hierarchical model Databases lecture 1a

  29. Brief History • Expansion of the possibilities (current) • Scientific use (Biological databases) • Images (Flickr.com, Google images/books) • Streaming data (YouTube) • Data mining (Machine learning) • Spatial information (Google Earth) • Knowledge (Ontology, Folksonomy, Wiki) Databases lecture 1a

  30. When not to use a DBMS • Too much overhead: • Hardware, software and training too costly • DBMS might be too general • DBMS might be too complex • The application is simple, well defined, will not change • Access speed should be very high • Only a single user Databases lecture 1a

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