Sample Exam Questions

From the objective of OSS-DB Exam Silver
- General Knowledge - database design, normalization

Sample Question


Choose the most appropriate one as an explanation of data normalization.

  1. To derive the best performance of the database, the data should be normalized.
  2. In order to minimize the capacity of the database, the data should be normalized.  
  3. Data should be normalized in order to improve the maintainability of the data. 
  4. To facilitate data backup, data should be normalized. 
  5. In order to simplify the SQL statement of data retrieval, the data should be normalized.

※This sample exam is different from those that appear in the actual OSS-DB Exam.

Answer and Explanation

To simplify data normalization, it means that data can be easily managed by eliminating duplication of data and redundancy. 

There are various degrees of normalization, and there are the first normal form, the second normal form, the third normal form, the Boyce-Codd normal form, the fourth normal form, and the fifth normal form as representative ones. 

In designing relational databases, especially the third normal form is very important, so please learn about the normalization method. 

When data is normalized, data duplication and redundancy are eliminated, so it is possible to prevent data inconsistency and loss due to data addition, update, deletion, etc. 

In other words, the maintainability of data is improved. 

However, if you normalize, SQL statements become complicated and search performance may deteriorate because you will join more tables and retrieve data. 

To optimize performance, it is also done to denormalize the data. 

As key columns and indexes are added instead of eliminating duplicate data, the size of the data does not necessarily become smaller due to normalization. 


Therefore, the correct answer is C.