A relational database management system (RDBMS) is a specific type of database that contain tables of data. These types of databases are often used in supporting either a single or several affiliated software applications. Specific database programming language is used to modify and report on the data. Several techniques can speed data retrieval and reduce duplication.
Organizations may use RDBMS for storing inventory, employee, customer, and other data. Users can interact with the system through software applications that include programming code to work with the database. These software applications can be traditional or web-based.
A relational database management system consists of tables with columns and rows. The column label identifies the data in the rows within the column. Each row contains the actual data for an instance of an entity, which can be a person, location, object, or idea. A customer database, for example, may have columns for the customer's ID, first name, last name, and email address, and each row contains an individual customer’s data.
These systems are accessed and updated using structured query language (SQL). To work with the data, a database developer will write programming statements called queries. Different brands of database management systems may require the use of different versions of SQL, though they have many similarities.
An RDBMS may use several types of tables. Base tables hold the entire set of data. Temporary tables store data that is being manipulated as a query is running. Results tables store the query outcomes.
Relational database management systems use several types of keys for retrieving data. A primary key identifies one particular instance of an entity. For an employee table, the primary key may be an employee identification number that each employee is permanently assigned to and which no other employee will use. Unique keys are other data elements that are also exclusive to each instance of an entity. For example, a retailer may assign inventory items with unique supplier item numbers.
A third type of key is a foreign key. In the relational model, it establishes relationships between entities. Using foreign keys, a relationship between a company’s customers and each customer's sales can be maintained without duplicating data in the relational database management system.
The speed of data retrieval is important, especially as the amount of data increases. A developer may add an index to an RDBMS to allow queries to run faster. The index typically uses a primary key, such as a tax identification number.