You can create query extensions in the module model by using the model editor.
A query extension enables you to customize the SQL that is used to retrieve data from the database. For example, you may want to use a different SQL statement to retrieve the data for basic campaign information.
For transactions that support pluggable SQL, it is preferable to use the pluggable SQL feature instead of query extensions to customize the query SQL.
See Defining inquiry levels for more information.
After creating the query extension, additional associated code is generated.