Databases can be searched by creating a query, of which there are two types: simple and complex.
A simple query uses one test on a single field to find records in a database. They are made up of three parts: a field name, an operator, and a value.
Examples of operators are equal to (=), more than (>), less than (<), and not equal to (<>).
An example of a simple query is:
Complex queries use more than one test, or look at more than one field. They are made up of two or more simple queries joined together by logical operators, such as AND, OR and NOT.
An example of a complex query is: