01 - DBMS

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Data accessdatabase access occur only through theexternal schema, which may coincidecompletely with the logical schema36
Data independence• physical independencethe logical and external levels are independentfrom the physical one– a relation is used in the same way whatever its physicalrealization (organization of files and their physicalallocation)– the physical implementation can changewithout having to change the programmes37
Page 1 and 2: Lesson 1 - Introduction to database
Page 3 and 4: Structured informationinformation i
Page 5 and 6: What happened earlier?●each appli
Page 7 and 8: DBMS●●●a Database (DB) is a s
Page 9 and 10: Storagedatabase systems use files t
Page 11 and 12: Processing information• goal: to
Page 13 and 14: Shared information• database shar
Page 15 and 16: Information System• data is conce
Page 17 and 18: Data Model• structures to be used
Page 19 and 20: Historical noteshierarchicalmid-60s
Page 21 and 22: Hierarchical model• restricted ty
Page 23 and 24: Relational model• data and relati
Page 25 and 26: Relational model• table = set of
Page 27 and 28: Example of relational DBSTUDENTSMat
Page 29 and 30: Historical notes●mid-80s: first o
Page 31 and 32: The three abstraction levels of a D
Page 33: A view (external schema)CoursesCour
Page 37 and 38: Schemes and instances• in every d
Page 39 and 40: Schemes andinstancesSTAFFNAME SURNA
Page 41 and 42: Database languages• data definiti
Page 43 and 44: Integrity●The data must satisfy
Page 45 and 46: Security• data must be protected
Page 47 and 48: Restore• To restore a correct dat
Page 49 and 50: DBA Tasks●design definition and d

01 - DBMS

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