How to: Use an Expression in a Precedence Constraint
This procedure describes how to add an expression to a precedence constraint by using the Precedence Constraint Editor dialog box. Before you can add an expression to a precedence constraint, the package must include at least two executables, either tasks or containers, and they must be connected by a precedence constraint.
To add an expression to a precedence constraint
In Business Intelligence Development Studio, open the Integration Services project that contains the package you want.
In Solution Explorer, double-click the package to open it.
Click the Control Flow tab.
On the design surface of the Control Flow tab, double-click the precedence constraint. The Precedence Constraint Editor opens.
Select Expression, Expression and Constraint, or Expression or Constraint in the Evaluation operation list.
Type an expression in the Expression text box.
To validate the expression syntax, click Test.
To save the updated package, click Save Selected Items on the File menu.