This file contains the DBMS Concepts which is useful for your interview preparation

2. Provide mechanisms for the manipulation of data

3. Ensure the safety of the data stored, despite system crashes or attempts at unauthorized access

5. Data Redundancy – Same data is duplicated in two or more files which may lead to update anomalies

6. Data Isolation – All the related data is not available in one file. Thus writing a new application program is difficult

7. Program / Data Dependence – Application programs are data dependent. It is impossible to change the physical representation (how the data is physically represented in storage) or access technique (how it is physically accessed) without affecting the application.

8. Lack of Flexibility – Only pre-determined request for information can be met. It is not flexible to satisfy unanticipated queries.

10. Allows for sharing of data among different users. Users are also able to access the database concurrently without facing the issues of inconsistent data.

11. Controls redundancy and inconsistency

12. Provides secure access to that database

13. Enforces integrity constraints (also known as business rules) by preventing the entity of invalid information into the database.

15. Conceptual Level

17. Give preference to a single attribute. The search algorithm gives better output with a single attribute primary key than with a composite attribute primary key

18. Give preference to the minimal composite key. A composite key is a collection of two or more attributes.

20. E-R Model

21. Record Based Logical Model

22. Hierarchical Data Model

23. Network Data Model

24. Relational Data Model

26. Banking: for customer information, accounts, loans and banking transactions

27. Universities: For student information, course registrations and grades.

28. Telecommunications: For keeping records of calls made, generating monthly bills, maintaining balances on prepaid calling cards and storing information about the communication networks.

30. One to Many Relationship

31. Many to One Relationship

32. Example: Many employees can work for only one department but one department can have many employees.

33. Many to Many Relationship

35. Find relationships: Identify the natural relationship and their cardinalities between the entities.

36. Identify the key attributes for every entity: Identify the attribute or set of attributes which can identify instance of entity uniquely

37. Identify other relevant attributes: Identify other attributes which are interest to business users and want to store the information in database.

38. Complete E-R diagram: Draw complete E-R diagram with all attributes including primary key.

40. Intuitive and helps in physical database creation.

41. Can be generalized and specialized based on needs.

42. Can help in database design

46. Remove subsets of data that apply to multiple rows of a table and place them in separate tables.

49. Emailid (Emailid decides Student#)

50. Student# Course# (decides rest of the attributes in Result table)

53. Create a separate table for each set of related data.