Question

please tell me how I can construct er diagram on Netflix and on hotelmangement in dbms and also tell me how I convert er diagram of Netflix in third normal form(3nf). also explain the queries .

Answer 1

Answer:

First of all, you need to identify some entities and their relations, for example User_account is an entity where we can get name, personal details as an attribute for that entity, and similarly movie is an entity with movie name, movie id, ratings of this attribute. After analysing and listing out these entitie along with their attributes, you can easily draw and ER diagram by examining thier relations and by connecting them on the basis of different relationships based on different scenarios.

To convert an ER diagram to a 3NF, logic design phase will help you out for the conversion. Logical design phase is process through the normalization.  Normalization is one of the key tenets in relational model design. It is the process of removing redundancy in a table so that the table is easier to modify.

It usually involves dividing an entity table into two or more tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of an attribute can be made in just one table and then propagated through the rest of the database via the defined relationships.

Normalization utilizes association among attributes within an entity table to accomplish its objective. Since an ERD also utilizes association among attributes as a basis to identify entity type structure, it is possible to apply normalization principles during the conceptual data modeling phase. Performing normalization during ERD development can improve the conceptual model, and speed its implementation. This paper outlines the application of normalization principles to ERD development during the conceptual modeling phase. There are various standards for ERD. In this paper, the Crow’s Foot notation is utilized.

Instead of applying normalization principles during the relational design portion of logical database design phase, it is better to apply them during the conceptual modeling phase. Due to the similarity in the notion of an entity type and a relation, normalization concepts when explained or applied to an ERD may generate a richer model. Also, such an application enables a better representation of user working requirements. This application now results in the specification of additional guidelines for refining an ERD. These guidelines can be stated as follows:

1. There should be only one dependency in each entity type where the determinant is the entity identifier.
2. There should not be any additional dependency among the non entity identifier attributes. Any such additional dependency should be represented by a new entity type with one-to-many relationship.
3. If there is a composite entity identifier of three or more attributes it should be ensured that there is only one multi-valued dependency among them.

Let me know if you have any doubts or if you need anything to change. 

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