DBMS Tutorial #11 | Cardinality Ratio (1:1, 1:N, N:1, M:N) | Mapping Cardinality in ER Model

In this lecture, we study Cardinality Ratio in the Entity Relationship Model in detail. This lecture builds directly on the previous discussion of Maximum and Minimum Cardinality, where maximum cardinality provided the foundation for understanding cardinality ratio. In this video, we learn: What is Cardinality Ratio? Why is Cardinality Ratio also called Mapping Cardinality? Understanding the connection with Set Theory and Mapping How to determine Cardinality Ratio step-by-step 1:1 (One-to-One) relationship 1:N (One-to-Many) relationship N:1 (Many-to-One) relationship N:M / M:N (Many-to-Many) relationship Examples of each type of cardinality ratio How to correctly identify the ratio from a given relationship A particularly important part of this lecture is learning how to conclude the cardinality ratio rather than simply memorizing 1:1, 1:N, N:1 and M:N. Connection with Previous & Upcoming Lectures In the previous lecture, we discussed Maximum and Minimum Cardinality. Maximum Cardinality → Foundation for Cardinality Ratio Minimum Cardinality → Foundation for Participation In the next lecture, we will study Participation, followed by numerical/problem-based questions. After completing the major concepts of the ER Model, we will move forward to the Relational Model in DBMS. 📌 This lecture is useful for B.Tech/M.Tech students, university examinations, competitive examinations, and anyone learning Database Management Systems. Topics Covered Cardinality Ratio | Mapping Cardinality | ER Model | 1:1 | 1:N | N:1 | M:N | Many-to-Many | One-to-Many | Many-to-One | DBMS Hashtags #DBMS #CardinalityRatio #ERModel #MappingCardinality #DatabaseManagementSystem #Database #ERDiagram #DBMSLecture #BTech #ComputerScience