We’ll cover the following
- Database Management System
- OS File System Storage Based Approach
- DBMS Approach
- Data Model
- E/R (Entity/Relationship) Model
What is a Database?
A collection of related pieces of data:
- Representing/capturing the information about a real-world enterprise or part of an enterprise.
- Collected and maintained to serve specific data management needs of the enterprise.
- Activities of the enterprise are supported by the database and continually update the database.
Data about students, faculty, courses, research-laboratories, course registration/enrollment etc.
Reflects the state of affairs of the academic aspects of the university.
Purpose: To keep an accurate track of the academic activities of the university.
Database Management System (DBMS)
A general purpose software system enabling:
- Creation of large disk-resident databases.
- Posing of data retrieval queries in a standard manner.
- Retrieval of query results efficiently.
- Concurrent use of the system by a large number of users in a consistent manner.
- Guaranteed availability of data irrespective of system failures.
OS File System Storage Based Approach
- Files of records – used for data storage
- Data redundancy – wastage of space.
- Maintaining consistency becomes difficult.
- Record structures – hard coded into the programs
- Structure modifications – hard to perform.
- Each different data access request (a query)
- Performed by a separate program.
- Difficult to anticipate all such requests.
- Creating the system
- Requires a lot of effort.
- Managing concurrent access and failure recovery are difficult.
- Separation of data and metadata
- Flexibility of changing metadata
- Program-data independence
Data access language
- Standardized – SQL
- Ad-hoc query formulation – easy
- Less effort required
- Concentration on logical level design is enough
- Components to organize data storage process queries, manage concurrent access, recovery from failures, manage access control are all available
Collection of conceptual tools to describe the database at a
certain level of abstraction.
- Conceptual Data Model
- A high level description
- Useful for requirements understanding.
- Representational Data Model
- Describing the logical representation of data without giving details of physical representation.
- Physical Data Model
- Description giving details about record formats, file structures etc.
E/R (Entity/Relationship) Model
- A conceptual level data model.
- Provides the concepts of entities, relationships and attributes.
The University Database Context
Entities: student, faculty member, course, departments etc.
Relationships: enrollment relationship between student & course, employment relationship between faculty member, department etc.
Attributes: name, rollNumber, address etc., of student entity, name, empNumber, phoneNumber etc., of faculty entity etc.
More details will be given in the E/R Model Module.
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Also Read – Introduction to Android Development