RDBs organize data in different ways. Each table is known as a relation, which contains one or more data category columns. Each table record (or row) contains a unique data instance defined for a corresponding column category. One or more data or record characteristics relate to one or many records to form functional dependencies. These are classified as follows:

• One to One: One table record relates to another record in another table.
• One to Many: One table record relates to many records in another table.
• Many to One: More than one table record relates to another table record.
• Many to Many: More than one table record relates to more than one record in another table.

RDB performs "select", "project" and "join" database operations, where select is used for data retrieval, project identifies data attributes, and join combines relations.

RDBs have many other advantages, including:

• Easy extendability, as new data may be added without modifying existing records. This is also known as scalability.
• New technology performance, power and flexibility with multiple data requirement capabilities.
• Data security, which is critical when data sharing is based on privacy. For example, management may share certain data privileges and access and block employees from other data, such as confidential salary or benefit information.