Database components include one or more tables for the data, a query language that retrieves specific data elements, and forms for entering or displaying data. Additional components include reporting tools and customized page views of data. Relational databases have a schema that defines the relationship between tables and may include components that automate routine tasks.
A simple database has a single table with rows for the data and columns that define the data elements. For an address book, the table columns define data elements such as name, address, city, state and phone number, while a table row, or record, contains data for each person in the book. The query language provides a way to find specific types of data in each record and return results that match the criteria. These results display in a form that uses the defined data elements but only shows records that meet the criteria. These three components make up almost every type of database.
Relational databases use multiple tables and define relationships between them using a schema in addition to data elements. Records and data elements from each table merge, based on the query, and display in the form. Routinely used queries often become reports. A report uses the same query but reports on changes in data over time.