Task 1.1
Disjoin subtype:
Basically disjoin subtype is a type of scenario that is often run into in data modelling. IN this modelling there is a one specific thing that this each subtype of entity is described with different own table. For example if we create a table name Animal there should be different entities for all subtype it should be like Living, instincts, marine lives, there are three different types of entity type that are disjoint types. (Enhanced E-R Model, 2001)
Overlapping:
Overlapping subtype are the subtypes that contain non-unique subsets of the super type entity relationship sets. In simple wording it can be said that this type of super type is contain one or more subtype on the same time. For example here if here we talk about a professor of the university he can be administrator of any department on the other hand a student can be a professor at that university. It means there is overlapping between student and professor. Figure 2
(E-R Modelling)
Task 1.2 …show more content…
It is also used to show and create the relationship between two entities. Redundant data wastes disks and create maintenance problems. It stores the each row only once and requires creating a good and professional database. Normalization is important in database because it makes the table more creative and full of knowledge and easily understandable for the users. With the use of normalization one can easily upgrade, and update the data in the