Relational Database Design (RDD)
Definition - What does Relational Database Design (RDD) mean?
Relational database design (RDD) models information and data into a set of tables with rows and columns. Each row of a relation/table represents a record, and each column represents an attribute of data. The Structured Query Language (SQL) is used to manipulate relational databases. The design of a relational database is composed of four stages, where the data are modeled into a set of related tables. The stages are:
- Define relations/attributes
- Define primary keys
- Define relationships
Techopedia explains Relational Database Design (RDD)
Relational databases differ from other databases in their approach to organizing data and performing transactions. In an RDD, the data are organized into tables and all types of data access are carried out via controlled transactions. Relational database design satisfies the ACID (atomicity, consistency, integrity and durability) properties required from a database design. Relational database design mandates the use of a database server in applications for dealing with data management problems.
The four stages of an RDD are as follows:
- Relations and attributes: The various tables and attributes related to each table are identified. The tables represent entities, and the attributes represent the properties of the respective entities.
- Primary keys: The attribute or set of attributes that help in uniquely identifying a record is identified and assigned as the primary key
- Relationships: The relationships between the various tables are established with the help of foreign keys. Foreign keys are attributes occurring in a table that are primary keys of another table. The types of relationships that can exist between the relations (tables) are:
- One to one
- One to many
- Many to many
An entity-relationship diagram can be used to depict the entities, their attributes and the relationship between the entities in a diagrammatic way.
- Normalization: This is the process of optimizing the database structure. Normalization simplifies the database design to avoid redundancy and confusion. The different normal forms are as follows:
- First normal form
- Second normal form
- Third normal form
- Boyce-Codd normal form
- Fifth normal form
By applying a set of rules, a table is normalized into the above normal forms in a linearly progressive fashion. The efficiency of the design gets better with each higher degree of normalization.