Data Modeling Frequently Asked Interview Questions and Answers – Part 2
1. What is normalization?
E.F. Codd gave some rules to design relational databases and the rules were focused on removing data redundancy which helps to overcome normal data modeling problems. The process of removing data redundancy is known as normalization.
2. What are the types of normalization?
First normal form, Second normal form, third normal forms are three types of normalization used in practice. Beyond these normal forms, Boyce-Codd fourth and fifth normal forms are also available.
3. What is De-Normalization?
De-Normalization is a process of adding redundancy to the data. This helps to quickly retrieve the information from the database.
4. What is data model Meta data?
You can take a report of the entire data model, or subject or part of the data model. The data about various objects in the data model is called as data model Metadata. .Data Modeling Tools have options to create reports by checking the various options. Either you can create logical data model Meta data of physical model Meta data.
5. What is data model repository?
Data Model and its relevant data like entity definition, attribute definition, columns, data types etc. are stored in a repository, which can be accessed by data modelers and the entire team.
6. What is forward engineering in a data model?
Forward Engineering is a process by which DDL scripts are generated from the data model. Data modeling tools have options to create DDL scripts by connecting with various databases. With these scripts, databases can be created.
7. What is reverse engineering in a data model?
Reverse Engineering is a process useful for creating the data models from database or scripts. Data modeling tools have options to connect to the database by which we can reverse engineer a database into a data model.
8. What is a subtype and super type entity?
An entity can be split into many entities (sub-entities) and grouped based on some characteristics and each sub entity will have attributes relevant to that entity. These entities are called subtype entities. The attributes which are common to these entities are moved to a super (higher) level entity, which is called as supertype entity.