Database Management System · Unit 3
Relational Data Model
Exam-focused notes for Relational Data Model (Database Management System, BIT202): what the TU syllabus asks and how it has actually been tested, with 5 solved past questions from this unit.
What this unit covers
- Relational model definition
- Relations versus flat files
- Relation, instance, and schema
- Attributes and domains
- Primary keys and foreign keys
- Integrity constraints
- Referential integrity
Relation, instance, and schema
Define relation, instance and schema. Explain with example [5]
A relation is a table with rows and columns. In the relational model, a relation is a mathematical concept based on set theory. It consists of: - A name (the relation name) - A set of attributes (columns) - A set of tuples (rows) A relation can be thought o...
Full solved answer →Relations versus flat files
What is Relational Data model? How Relation is different than Flat file? [5]
The Relational Data Model is a data model that represents data in the form of two-dimensional tables called relations. It was proposed by E.F. Codd in 1970 and is the foundation of most modern database management systems (RDBMS). Term Description ----------...
Full solved answer →Primary keys and foreign keys
What is Primary key and Foreign Key? Why is this required in the DBMS? [5]
--- A Primary Key is a column (or a set of columns) in a table that uniquely identifies each row/record in that table. - Must be unique for every record (no two rows can have the same primary key value) - Cannot contain NULL values - A table can have only o...
Full solved answer →Integrity constraints
What is Integrity constraint? What are the three main categories of Integrity constraints. [5]
An Integrity Constraint is a rule or condition imposed on a database to ensure the accuracy, consistency, and validity of data stored in the database. Integrity constraints prevent invalid data from being entered into the database and maintain the correctne...
Full solved answer →Define domain constraint and referential integrity constraint. [5]
--- Definition: A domain constraint specifies that the value of each attribute in a relation must be an atomic (indivisible) value drawn from the domain (set of permissible values) defined for that attribute. In other words, for every tuple in a relation, t...
Full solved answer →Make Unit 3 stick
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