The means of doing this is through queries written in SQL, the industry-standard query language. With SQL, developers can write very sophisticated queries against their databases. The key properties that must be considered for TQuerys are somewhat different than those for TTables. Parameters can be used in a query in order to make the query more generic. The Params property allows the developer to specify the datatypes and default values of parameters used in a query.
Additional information follows below.
BDE has the ability to create 'live' updatable queries for databases that support the necessary pointer or cursor functionality. The SQL property allows you to specify the SQL query. If you double-click on this property, a List Editor window will appear which presents an editor. Simply type in the SQL command for the TQuery and click the OK button. Similar to the Active property of the TTable, the Active property of the TQuery opens the DataSet and allows the developer to see the actual data that is returned to the application from the query during design or runtime mode.