An operator that joins persistent objects on a specified condition, and calculates aggregate functions against matching objects.
public class JoinOperand : CriteriaOperator, IAggregateOperand, ICustomAggregateOperand
Public Class JoinOperand Inherits CriteriaOperator Implements IAggregateOperand, ICustomAggregateOperand
Related API Members
The following members accept/return JoinOperand objects:
Use the JoinOperand to build criteria and calculate aggregate functions using the properties of persistent objects that don't have explicitly defined associations. Persistent objects, to which the current JoinOperand is applied, are called parent objects for the join. To specify the type of persistent objects to be joined with parent objects, use the JoinOperand.JoinTypeName property.
The JoinOperand does the following:
- Joins the objects on a condition specified via the JoinOperand.Condition property.
- Calculates aggregate functions using expressions created with property values of matching objects. To specify the aggregate function and aggregated expression, use the JoinOperand.AggregateType and JoinOperand.AggregatedExpression properties.
Refer to the Free Joins help topic, to learn how to use the JoinOperand.
- For performance reasons, we recommend that you not use the JoinOperand when filtering or sorting the XPCollection on the client side, as this significantly increases the number of queries sent to the server.
- JoinOperand may produce null instead of zero for an empty collection on a server side.