Solution

Disjoint Constraint: It requires that higher level entity set belongs to only one lower-level entity set. Let there be an account entity can be either a savings account or a current account, but cannot be both. Therefore, account is higher level entity and saving account and current account are lower level entities.

Partial Participation: It is not based on Generalisation / Specialisation. It allows the flexibility that the entity in the entity set may or may not participate in the relationship. Let there be an employee entity that manages department entity. Here, 'manages' is a relationship between employee and department. But not every employee manages department, only manager manages department. Hence, participation of employee entity is partial.

Overlapping Constraints: Here, the same higher level entity may belong to more than one lower-level entity set. Let there be a person entity that may belong to both customer entity and employee entity, hence, it is an overlapping constraint.

Total Specialisation: Each higher-level entity must belong to a lower-level entity set. Let us consider a college where an employee must be either teaching faculty, non-teaching faculty or both. Here, employee entity must belong to Lower level entity.

• Considering the above constraints, Total Specialisation and Overlapping Constraints must be considered when modelling class / subclass concepts in ERD for the above problem.