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Most relational database systems allow the creation of queries (sometimes called views). A query extracts information from the tables in the database; a query selects and defines a group of records that fulfill a certain condition. Most database outputs are based on queries that combine, filter, or sort data before it’s displayed. Queries are often called from other database objects, such as stored procedures, macros, or code modules. In addition to extracting data from tables, queries can be used to change, add, or delete database records.

An example of a query is when a person at the sales office tells the database, “Show me all customers, in alphabetical order by name, who are located in Massachusetts and who made a purchase over the past six months.” Or “Show me all customers who bought Chevrolet car models within the past six months, and display them sorted by customer name and then by sale date.”

Rather than ask the question using English words, a person uses a special syntax, such as Structured Query Language (or SQL), to communicate to the database what the query will need to do.