
Chapter 12. Custom Queries 231
query does not return any data a DatabaseQuerySpec instance will be used
instead of a DatabaseSelectQuerySpec instance, and of course no output
shape needs to be defined.
Example of a Fixed Custom Query
Suppose we wish to query the BankAccount home forall accounts that have a
balance greater than 10000.00. These accounts are gold accounts, owned by
the bank’s valued customers, and we would like to retrieve this information
for use in an application. Coding this query using the methods provided by
the home collection class and Vector manipulation would be cumbersome. A
convenient approach is to create a custom query call ...