E-R vs Starschema

7,665 views

Published on

Hera are some slide for the discription of E-R Model and Star Schema

Published in: Education, Technology
2 Comments
3 Likes
Statistics
Notes
No Downloads
Views
Total views
7,665
On SlideShare
0
From Embeds
0
Number of Embeds
8
Actions
Shares
0
Downloads
145
Comments
2
Likes
3
Embeds 0
No embeds

No notes for slide

E-R vs Starschema

  1. 1. ER-MODEL STAR SCHEMA
  2. 2. E-R ( Entity-Relationship) Modeling <ul><li>The Entity-Relationship model provides a informal and convenient model for communication between users and the DBA for the purpose of modeling the data’s structure. </li></ul>
  3. 4. Components used in developing an E-R Model <ul><li>ENTITY : Anything that exists. For example Each CHAIR is an Entity, Each person is an Entity </li></ul><ul><li>ENTITY SET: It is group of similar entities forms an Entity Set. Example All persons </li></ul>
  4. 5. Contd…. <ul><li>ATTRIBUTES: It is the properties that characterize an entity set. Example Name , Address , Skill etc </li></ul><ul><li>RELATIONSHIP: It is association between two or more entities. Example we may have the relationship that an employees works in a department. </li></ul>
  5. 6. EMP DEPT SN NAME LOC Did Dname Bud. WorkIN Since Attri: SN, NAME, LOC Attri: Did, Dname, Budget
  6. 7. Dimensional Modeling <ul><li>Dimensional Modeling is a logical design technique present the data in a standard framework that allows for high-performance access. In this design model all the data is stored in two types of tables - Facts table and Dimension table. </li></ul>
  7. 8. STAR SCHEMA
  8. 9. <ul><li>Star schema is a type of organizing the tables such that we can retrieve the result from the database easily and fastly in the warehouse environment. </li></ul><ul><li>It contains one fact table and many dimension table. Fact table contains facts or measures. </li></ul><ul><li>Dimension tables hold descriptive data that reflects the dimensions, or attributes. </li></ul>
  9. 10. Difference between E-R Modeling and Dimentional Modeling.? <ul><li>Basic diff is E-R modeling will have logical and physical model. </li></ul><ul><li>Dimensional model will have only physical model. </li></ul><ul><li>E-R modeling is used for normalizing the database design. </li></ul><ul><li>Dimensional modeling is used for de-normalizing the design. </li></ul>

×