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Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
Dmbs chapter vi
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Dmbs chapter vi

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  • 1. Subject Name Code Credit Hours Database System COMP 219 3 Chapter VI
  • 2. Subject Name Code Credit Hours Database System COMP 219 3 E-R Diagram • Symbol Description Entity Type Attribute Key Attribute
  • 3. Subject Name Code Credit Hours Database System COMP 219 3 E-R Diagram Symbol Description Composite Attribute Multivalued attribute Attribute
  • 4. Subject Name Code Credit Hours Database System COMP 219 3 E-R Diagram Symbol Description Derived Attribute Relationship
  • 5. Subject Name Code Credit Hours Database System COMP 219 3 E-R Diagram • Symbol Description Identifying Relationship Weak Entity Type
  • 6. Subject Name Code Credit Hours Database System COMP 219 3 E-R Diagram • Symbol Description E1 E2R Total participation of E2 in R & Partial Participation of E1 in R E1 E2R 1 1 Cardinality Ratio E2R Min,max Structural constraints (min,max) on participation of Environmental in R
  • 7. Subject Name Code Credit Hours Database System COMP 219 3 Recursive Relationship • If the same entity type partcipates in a relationship more than once in different roles. • E.g.. Employee Supervising Supervisor Supervise
  • 8. Subject Name Code Credit Hours Database System COMP 219 3 Design of an E-R Database Schema The steps involved in designing an E-R database schema are, • Identify entity types and their entity sets. • List out the attributes of each entity type. • Relate several entities by specifyiing some relationship that exists among them. • Specify some attributes of relation if any. • Specify Generalization and specialization any exists. • Specify Aggregation (global) if any used.
  • 9. Subject Name Code Credit Hours Database System COMP 219 3 Design Process: • The main phases involved in designing a ER db schema is shown below, Mini world Requirements collection & Analysis Data Requirements Conceptual Design Conceptual schema Logical Design Physical design Logical schema Internal Schema Transaction implementation Functional Requirements Functional Analysis High level Transaction specification Application program Design App.pgms DBMS Independen t DBMS Specific
  • 10. Subject Name Code Credit Hours Database System COMP 219 3 Requirements collection & Analysis • The db designers interview db users to understand & document their requirements. • They find out data requirements (what data are stored in the db). Conceptual Design: • Once the requirements are documented , the next step is to create conceptual schema which carried out in conceptual design Phase. • It describes the structure of a db in the form of entity type, relationship among them & constraints.
  • 11. Subject Name Code Credit Hours Database System COMP 219 3 Logical Design • The actual implementation of the db is carried out using DBMS. Physical Design  The last phase is the internal storage structures, indexes, access paths, and file organizations for the db files are specified.  In parallel with these activities, Application programs are designed and implemented as db transactions.
  • 12. Subject Name Code Credit Hours Database System COMP 219 3 EER Model- Enhanced or Extended E-R model • Using E-R model only the basic features of a db. • Some enhanced features such as Specialization, Generalization, Union & aggregation can be shown using EER model. A. SPECIALIZATION: The process of designating sub grouping within an entity set..
  • 13. Subject Name Code Credit Hours Database System COMP 219 3 E.g….. Employee IS A Secretary Technician Manager eid ename eaddr Job Typing speed Mgrid
  • 14. Subject Name Code Credit Hours Database System COMP 219 3It is also represented as Employee eid ename eaddr Job d Secretary Technician Manager d Job Type Salary Type Hourly Regular Defining attribute Sub classes
  • 15. Subject Name Code Credit Hours Database System COMP 219 3 Generalization •The process of defining a generalized entity type from the given entity types.
  • 16. Subject Name Code Credit Hours Database System COMP 219 3E.g… CAR TRUCK PriceMax speed Vehicle ID No. of seats Vehicle ID Price No. Of Axles Tonnage
  • 17. Subject Name Code Credit Hours Database System COMP 219 3 Vehicle Vehicle ID Price d CAR TRUCK Max speed No. of seats Tonnage No. Of Axles
  • 18. Subject Name Code Credit Hours Database System COMP 219 3 History of Database Systems • 1950s and early 1960s: – Data processing using magnetic tapes for storage • Tapes provide only sequential access – Punched cards for input • Late 1960s and 1970s: – Hard disks allow direct access to data – Network and hierarchical data models in widespread use – Ted Codd defines the relational data model • Would win the ACM Turing Award for this work • IBM Research begins System R prototype • UC Berkeley begins Ingres prototype – High-performance (for the era) transaction processing
  • 19. Subject Name Code Credit Hours Database System COMP 219 3 History (cont.) • 1980s: – Research relational prototypes evolve into commercial systems • SQL becomes industrial standard – Parallel and distributed database systems – Object-oriented database systems • 1990s: – Large decision support and data-mining applications – Large multi-terabyte data warehouses – Emergence of Web commerce • 2000s: – XML and XQuery standards – Automated database administration

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