Question

In some large organizations where there are several buildings and floors we see room numbers that encode information about the building, floor, and room number. For example in case the room 3C13 stands for room 13 on the third floor of the Centennial building. Suppose we need to include Room in an ERD. How would you represent the room number given that you must include atomic attributes only?

Short answer

The atomic attributes for the 'Room' entity in the ERD would be 'Building', 'Floor', and 'Room Number'. Each room can be uniquely identified by these three attributes.

Step-by-step solution

Understand Atomicity

Atomicity in database terms means that data cannot be further divided. Now consider the room number attribute '3C13'. It's made up of three separate pieces of information, the room number '13', the floor number '3', and the building 'C'. To maintain atomicity, these should be split into three separate attributes.

Break Down the Room Number

Separate the room number '3C13' to 'Building C', 'Floor 3', and 'Room 13'. Each of these is now an atomic attribute.

Create Entity and Attributes

Create an entity called 'Room' with three attributes. These attributes are 'Building', 'Floor', and 'Room Number'.

Diagram the ERD

Each room should be uniquely identified by its floor, building, and room number. 'Room Number' can be the primary key including 'Building' and 'Floor'.

Key concepts

Entity Relationship Diagram (ERD)

An Entity Relationship Diagram (ERD) is a way to visually represent the structure of a database. It helps in identifying different entities involved in a system and the relationships between them.

When you create an ERD, you define entities—which can be objects, concepts, or people—and illustrate how these entities relate to each other. Each entity is represented as a rectangle, and relationships are depicted with lines connecting the rectangles. This method of visualization simplifies complex data systems, making it easier for users and developers to understand.

For example, in our scenario, the 'Room' entity can be shown with attributes linked to it. These attributes, like 'Building', 'Floor', and 'Room Number', help in providing a clear understanding of how rooms are organized within the different buildings and floors. Using ERDs, one can easily locate potential issues in the database design early in the process, saving time and effort in later stages.

Room Number Encoding

Room number encoding is a system that combines multiple pieces of information into a single code to make data representation simpler and more efficient.

In large organizations, where there are several buildings and floors, room numbers often encode details about their location. For instance, the room number '3C13' contains three vital bits of information:

• '3' indicates the floor number.
• 'C' signifies the building name or code.
• '13' is the specific room number on that floor.

Although encoding data like this might seem convenient, it poses challenges when building a database that adheres to atomicity.

Splitting these pieces allows for a more organized and beneficial database design. Each piece of data can then be stored as a separate entity or attribute, making it easier to query and manipulate. This separation also allows more flexibility, enabling updates to be made independently without affecting other components.

Database Attributes

Database attributes are characteristics or properties of an entity in a database. They provide detailed information about the entity they belong to, acting as the "columns" of a database table.

An attribute should be atomic, meaning it should be indivisible. This ensures that each attribute captures a single type of data element without including multiple pieces of information.

In the context of the room number '3C13', we should split this encoded data into distinct attributes for ease of database management. The separate attributes would be:

• Building: the code or name of the building, such as 'C'.
• Floor: the floor number, such as '3'.
• Room Number: the specific room, such as '13'.

By defining each attribute clearly, databases can better maintain, query, and manage data. This organization aligns with best practices, promoting efficient database systems that are scalable and easy to navigate.