Using Caché Objects - InterSystems Documentation

Class Queries
8.1 Query Basics
The process for creating and using a class query is:
1. Define the query. The simplest way to do this is using the New Query Wizard in the
Caché Studio.
2. Invoke the query. This can be using the %New method of the %Library.ResultSet class
within server-based methods; using the Java or ActiveX result set classes that are part of
the Caché Java and ActiveX bindings, respectively; or as a OBDC or JDBC stored procedure.
3. Once the query has returned a %Library.ResultSet object (often known as a result set),
fetch data from it. (Further information on the result set processing is available in the
“Dynamic SQL” chapter of the Using Caché SQL guide.
4. When processing is complete, close the result set.
8.1.1 The Structure of a Class Query
The simplest query is of type %SQLQuery and simply contains an SQL SELECT statement.
Such a query performs all processing for the application. It is of the form:
Query QueryName(Parameter As %String) As %SQLQuery
{
SELECT MyProperty, MyOtherProperty FROM MyClass
WHERE (MyProperty = "Hello" AND MyOtherProperty = :Parameter)
ORDER BY MyProperty
}
You can also create a query of type %Query, which allows the application to perform its own
custom processing. Such a query is of the form:
8.1.2 Query Keywords
You can modify a query definition through the use of one or more query keywords. Each
keyword is optional and has a default value if not explicitly specified. The major query keywords
are:
Description
Provides an optional description of the query; Caché does not use this description.
By default, queries have no description.
56 Using Caché Objects