For those not acquainted with the vernacular of relational databases, many frequently used terms can be hard to grasp. These terms are often difficult to comprehend, but the concepts they describe can be illustrated in plain English. When a database administrator or developer is working with someone not fluent in relational database terminology, it is helpful to rephrase explanations to avoid words not commonly understood outside the database industry.
Entities are things. More specifically, entities are the things record in the database. Entities can be objects like people and places, or they can be non-physical records such as events. Entities are made up of attributes. Although entities are grouped together based upon what they are, attributes make each entity unique (Senn, 2004). For example, cars are a type of entity. All cars share common attributes such as an engine size, color, and number of seats. The difference in these attributes is what makes them unique.
Data integrity is another commonly heard term in the relational database industry. Data integrity refers to the validity of the data within the database. Databases should be designed to ensure the highest level of data integrity. If the validity of the data within the database is suspect, then the information derived from that data is suspect as well. One way to control data integrity is to apply a domain to an attribute. A domain is simply a list of values that are acceptable for any given attribute (Hernandez, 2003). For example, Henry Ford famously offered his Model T only in black. Therefore, the domain for the color attribute of the Model T entity had only one value: black.
Relational databases are complicated pieces of software. The relational database model increases this complexity by adding a layer of jargon. Individuals new to databases should be encouraged to learn the concepts behind the relational database model, but also understand that the terminology of the model is often difficult to comprehend. By focusing first on the concepts and then mastering the terminology, a new database user will enjoy greater success than if they were instead mired under a wave of jargon.
Hernandez, M. J. (2003). Database design for mere mortals: A hands-on guide to relational database design (2nd ed.). Boston: Pearson.
Senn, J. A. (2004). Information technology: Principles, practices, opportunities (3rd ed.). Upper Saddle River, NJ: Pearson.