A statement expressed in Siebel Query Language. The application evaluates whether the expression is true or false. If true, the data validation manager proceeds to evaluate the next rule. If false, the application performs the actions defined for the rule.
You can refer to a business component field value using the notion [Field]. For example, if the business component of the rule is Opportunity, then an expression [Sales Stage] IS NOT NULL means that you want to know of the Sales Stage field of the Opportunity business component contains a value or not.
You can use the syntax [BC.Field] to refer to a field of a business component different from the one of the validation rule. For example, you may have a rule which has its business component set as Opportunity. You can write the following expression stating what is valid:
[Sales Stage] IS NOT NULL AND [Account.Status] = "Active"
[Account.Status] refers to the Status field of the Account business component. Without a prefix, [Sales Stage] refers to the Sales Stage field of the business component (Opportunity) of the rule.
You can also use the syntax
[&Argument] to refer to a rule set argument. For example, you may have a rule expression
[&Answer] = "Yes". Here the rule set argument Answer has already been defined in the Arguments List Applet. Once defined, the argument becomes a business service input argument which you can populate with dynamic values at run time (for example, through a workflow).
You can either enter the statement directly in the field or click the Expression select button to launch the Expression Designer. The Expression Designer allows you to construct an expression by pointing and clicking on a pop up window, perform syntax validation, and lookup definitions of built-in functions supported by the Siebel Query Language.
For more information about the Expression Designer, see Developing and Deploying Siebel Business Applications.