Queries

Databases allow us to store and filter data to find specific information. A database can be queried using a variety of methods, although this depends on the software you are using.

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Databases can use query languages or graphical methods to interrogate the data.

Query language

Query language is a written language used only to write specific queries. This is a powerful tool as the user can define precisely what is required in a database. SQL is a popular query language used with many databases.

Query by example (QBE)

QBE allows the user to create queries based on a template, usually a set of filters presented in a graphical form. If you are using database software it might have an option to connect blocks and set the filters you want. The system presents a blank record and lets you specify the fields and values that define the query.

Database management software like MySQL, Microsoft Access and Oracle have front-end graphical interfaces which make it easier to run QBE queries.

BBC's Simon Lumb explains what SQL is and how it is used in databases