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Slide 2 data models
The document discusses several data models: hierarchical, network, relational, object-oriented, object-relational, deductive, and ER models. It provides descriptions of each model, including their key features, advantages, and disadvantages. The relational model is highlighted as the most popular currently due to its structural independence, conceptual simplicity, and powerful query capabilities using SQL. The ER model is also discussed as defining the conceptual view of databases through modeling real-world entities and relationships.
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Slide 2 data models
- 1. Prepared by VisakhV, Assistant Professor,Dept. of CSE, LBSITW DATA MODELS
- 2. DATA MODELS • Abstractform of any system • Conceptual tool for describing data, data relationship, semantics, consistency constraints Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 3. Type of DATAMODELS 1)Hierarchical Model 2)Network Model 3)Relational Model 4)ER Model 5)Object Oriented Model 6)Object Relational Model 7)Deductive / Inference Model Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 4. 1)Hierarchical Model •Oldest database model. (1950’s) • Tree structure is most frequently occurring relationship. • organize data elements as tabular rows Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 5. Advantages • Simplicity • Datasecurity • Data Integrity • Efficiency : When contains large no of relations Disadvantages • Implementation complexity • Database management problem : maintaining difficult • Lack of structural independence • programming complexity • Implementation problems (N:N difficult, only 1:N) Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 6. Prepared by VisakhV, Assistant Professor,Dept. of CSE, LBSITW
- 7. Prepared by VisakhV, Assistant Professor,Dept. of CSE, LBSITW
- 8. 2) Network Model •Graph structure • Allow more connection between nodes • Ex: A employee work for two department is not possible in hierarchical model, but here it is possible Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 9. Advantages • Conceptual simplicity •handle more relationships • Ease of data access • Data integrity : does not allow a member to exist without an owner • Data independence : isolate programs from complex physical storage • Database standards : like DDL, DML Disadvantages • System Complexity : not user friendly, navigation difficult, user must familiar with internal structure • Absence of structural independence :database structure change then modify application program Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 10. Prepared by VisakhV, Assistant Professor,Dept. of CSE, LBSITW
- 11. 3) Relational Model •Datain the form of table • each table application entity • each row instances of that entity • SQL serves as a uniform interface for users providing a collection of standard expression for storing and retrieving data • Most popular database model Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 12. Formal Relational termsInformal Equivalence Relation Table Tuple Row/record Cardinality of relation Number of rows Attribute Columns/field Degree of relation Number of columns Primary Key Unique identifier Domain A pool of values from which the values of specific attributes of specific relations are taken Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 13. Prepared by VisakhV, Assistant Professor,Dept. of CSE, LBSITW
- 14. Advantages • Structural independence •Conceptual simplicity • Design , implementation , maintenance and usage ease • Adhoc Query capability •Very powerful •Flexible •Easy to use query capability >SQL : makes adhoc queries a reality : It is 4GL Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 15. Disadvantages • Hardware Overheads(Today it is not a big deal…) • Ease of design leads to bad design • Information island phenomena •It will prevent information integrity • cause redundancy • cause inconsistency Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 16. 4) Object orientedmodel • Handling complex information • represents entity as a class • Suited for •Multimedia applications •Complex relation relationships • can hold data,text,pictures,voice and video Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 17. Prepared by VisakhV, Assistant Professor,Dept. of CSE, LBSITW
- 18. Advantages • Large numberof different data types • Its features improve productivity • Inheritance • Polymorphism • Dynamic binding Disadvantages • Difficult to maintain : schema migration (real world data model is not static) • Not suited for all applications (Performance degradation may happen) Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 19. 5) Object relationalmodel • Combines the advantages of relational database + Object oriented programming • Database and is manipulated collectively with queries + A programming API for storing and retrieving objects Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 20. 6) Deductive model •It can make deductions (i.e., conclude additional facts) based on rules and facts stored in the (deductive) database • Datalog : is the language typically used to specify facts, rules and queries in deductive databases Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 21. 7) ER model •Developed by Peter Chen and published in a 1976 paper • Defines the conceptual view of database • It works around real world entity and association among them • At view level, ER model is considered well for designing databases. • Terminologies : • Entity • Attribute •Simple attribute: •Composite attribute: •Derived attribute: •Single-valued attribute: •Multi-value attribute: • KEYS : PRIMARY KEY, SUPER KEY, FOREIGN KEY, CANDIDATE KEY • CARDINALITIES Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW
- 22. Prepared by VisakhV, Assistant Professor,Dept. of CSE, LBSITW
- 23. Advantages • Easy tounderstand • Helps in physical database creation Disadvantages • May contain some amount of ambiguities or inconsitency. • Sometimes diagrams may leads to misinterpretations. Prepared by Visakh V, Assistant Professor,Dept. of CSE, LBSITW