Comments on MIS Week-2 Questions
- What advice would you give to make sure an ERD accurately represents the business event it is supposed to capture?
In order to capture a business event and represents it in ERD (The Entity Relationship Diagram) in an accurate manner, my advice is to analyze the process (business situation), map it with three key elements (entity, attribute, and relationship), and normalize it by following three rules.
First of all, track through the process, and then decode an entity, which is being described and a uniquely identifiable thing, such as person and order. It is most likely following by words “described by” or “defined by.” Cardinality defines the rules of the association between entities.
Secondly, find out each entity’s attribute, which is a character of an entity or relationship, for example, first name or order number. This describes the entity and would repeat like “order number” and “order data.”
Finally, build the relationship between entities and its attributes by following three rules: create a table (set of related records: set of related fields) for each entity, create table fields (set of related characters: single letter or number) for every entity’s attributes, and create a new table showing the relationship between the entities tables. The primary key field of one table put into “many” (other) tables as a foreign key field.
By organizing data to minimize redundancy, the normalization processing is not only saving space but also avoiding mistakes by repeating the entering of multiple data. In this way, retrieve the date from the database (set of related tables) is relative easy for future use.