ANSI-SPARC  3-Level Architecture
<ul><li>ANSI-SPAR C </li></ul><ul><li>American National Standards Institute - Standards Planning And Requirements Committe...
<ul><li>ANSI-SPARC </li></ul><ul><li>First proposed in 1975, but never became a formal standard. </li></ul><ul><li>Most mo...
<ul><li>The objective of the three-level architecture is to separate the users’ view(s) of the database from the way that ...
ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level
ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level External Schema 1 External Schema n Concept...
ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level External Schema 1 External Schema n Concept...
ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level External Schema 1 External Schema n Concept...
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
ANSI-SPARC - Star Trek style - v2.0
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ANSI-SPARC - Star Trek style - v2.0

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ANSI-SPARC - Star Trek style - v2.0

  1. 1. ANSI-SPARC 3-Level Architecture
  2. 2. <ul><li>ANSI-SPAR C </li></ul><ul><li>American National Standards Institute - Standards Planning And Requirements Committee </li></ul>
  3. 3. <ul><li>ANSI-SPARC </li></ul><ul><li>First proposed in 1975, but never became a formal standard. </li></ul><ul><li>Most modern commercial DBMS are based on this system. </li></ul>
  4. 4. <ul><li>The objective of the three-level architecture is to separate the users’ view(s) of the database from the way that it is physically represented. This is desirable since: </li></ul><ul><ul><li>It allows independent customised user views: Each user should be able to access the same data, but have a different customised view of the data. These should be independent: changes to one view should not affect others. </li></ul></ul><ul><ul><li>It hides the physical storage details from users: Users should not have to deal with physical database storage details. They should be allowed to work with the data itself, without concern for how it is physically stored. </li></ul></ul><ul><ul><li>The database administrator should be able to change the database storage structures without affecting the users’ views: From time to time rationalisations or other changes to the structure of an organisation’s data will be required. </li></ul></ul><ul><ul><li>The internal structure of the database should be unaffected by changes to the physical aspects of the storage: For example, a changeover to a new disk. </li></ul></ul><ul><ul><li>The database administrator should be able to change the conceptual or global structure of the database without affecting the users: This should be possible while still maintaining the desired individual users’ views. </li></ul></ul>
  5. 5. ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level
  6. 6. ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level External Schema 1 External Schema n Conceptual Schema Internal Schema
  7. 7. ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level External Schema 1 External Schema n Conceptual Schema Internal Schema Data Definition Data Manipulation Data Administration Associated Languages
  8. 8. ANSI/SPARC 3-Level Architecture External Level Conceptual Level Internal Level External Schema 1 External Schema n Conceptual Schema Internal Schema Data Definition Data Manipulation Data Administration Associated Languages

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