Different data models
- 1. DIFFERENT DATA MODELS Create By : Madusha Udayangani Esoft Metro campus (kurunegala) HND com- 15 10086
- 2. â˘A data model is a conceptual representation of the data structures that are required by a database. â˘To use a common analogy, the data model is equivalent to an architect's building plans. â˘A data model is independent of hardware or software constraints. DATA MODELING
- 3. IMPORTANCE OF DATA MODELS ⢠Data models ďź Representations, usually graphical, of complex real- world data structures ďź Facilitate interaction among the designer, the applications programmer and the end user ⢠End-users have different views and needs for data ⢠Data model organizes data for various users
- 4. TYPE OF DATA MODELS ⢠FILE BASED APPROACH ⢠Hierarchical Model ⢠Network Model ⢠Relational Model ⢠ER Model ⢠Object Oriented Model ⢠Object Relational Model ⢠Deductive / Inference Model
- 5. FILE BASED APPROACH ⢠A collection of un-related files and a collection of application programs that perform services for the end-users, such as the production of reports. Each program defines and manages its own data. 1.Traditionally each department in a company would maintain its own collection of files. 2.The data processing department would write programs for each application each office needed performed.
- 6. â˘Separation and isolation of data â˘Duplication of data â˘Incompatible File Formats â˘Data dependence â˘Fixed queries/proliferation of application programs â˘Inability to generate timely reports LIMITATIONS OF THE FILE-BASED APPROACH
- 7. HIERARCHICAL MODEL ⢠Oldest data base model. (1950âs) ⢠Tree structure is most frequently occurring relationship. ⢠organize data elements as tabular rows
- 8. Advantages ⢠Simplicity ⢠Data security ⢠Data Integrity ⢠Efficiency : When contains large no of relations Disadvantages ⢠Implementation complexity ⢠Database management problem : maintaining difficult ⢠Lack of structural independence ⢠programming complexity
- 9. 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
- 10. Advantages ⢠Conceptual simplicity ⢠handle more relationships ⢠Ease of data access ⢠Data integrity â˘Data independence ⢠Database standards Disadvantages ⢠System Complexity ⢠Absence of structural independence
- 11. Relational Model â˘Data in the form of table ⢠each table ď application entity ⢠each row ď instances of that entity â˘SQL serves as a uniform interface for users providing a collection of standard expression for storing and retrieving data ⢠Most popular database model
- 12. Formal Relational terms Informal 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
- 13. Advantages ⢠Structural independence ⢠Conceptual simplicity ⢠Design , implementation , maintenance and usage ease â˘Query capability â˘Very powerful â˘Flexible â˘Easy to use query capability
- 15. The main highlights of relations model â˘Data is stored in tables called relations. â˘Relations can be normalized. â˘In normalized relations, values saved are atomic values. â˘Each row in a relation contains a unique value. â˘Each column in a relation contains values from a same domain.
- 16. Comparison between hierarchical model, network model and relational model
- 17. Characteristic Hierarchical model Network model Relational model Data structure ⢠One to many or one to one relationships. ⢠Based on parent child relationship. ⢠Allowed the network model to support many to many relationships. ⢠A record can have many parents as well as many children. ⢠One to One, One to many, Many to many relationships. ⢠Based on relational data structures. Data manipulation ⢠Does not provide an independent stand alone query interface ⢠retrieve algorithms are complex and asymmetric ⢠CODASYL (Conference on Data Systems Languages) ⢠Retrieve algorithms are complex and symmetric ⢠Relational databases are what brings many sources into a common query (such as SQL) ⢠Retrieve algorithms are simple and symmetric
- 18. Characteristic Hierarchical model Network model Relational model Data integrity ⢠Cannot insert the information of a child who does not have any parent ⢠Multiple occurrences of child records which lead to problems of inconsistency during the update operation ⢠Deletion of parent results in deletion of child records ⢠Does not suffer form any insertion anomaly. ⢠Free from update anomalies ⢠Free from delete anomalies ⢠Does not suffer from any insert anomaly. ⢠Free form update anomalies ⢠Free from delete anomalies
- 19. Â why relational model best fits the DAD assignment scenario
- 20. ⢠Tables are basic building blocks of a relational database. ⢠Keys are central to the use of relational tables. ⢠Keys define functional dependencies ďź Candidate key ďź Primary key ďź Secondary key ďź Foreign key
- 21. ⢠Each table row must have a primary key which uniquely identifies all attributes ⢠Tables can be linked by common attributes. Thus, the primary key of one table can appear as the foreign key in another table to which it is linked ⢠The relational model supports relational algebra functions: SELECT, DELETE, LIKE, UPDATE, OR AND. ⢠Good design begins by identifying appropriate entities and attributes and the relationships among the entities.
- 22. REFERENCES - http://www.tutorialspoint.com/dbms/pdf/dbms_data_models.pdf - What are some advantages of using the database management system approach rather than the file system approach? - Quora www.quora.com - http://www.teach- ict.com/as_as_computing/ocr/H447/F453/3_3_9/database_design/miniwe b/pg8.htm# www.teach-ict.com
- 24. Create By : Madusha Udayangani Esoft Metro campus (kurunegala) HND com- 15 10086