Database Reference
In-Depth Information
Precedence constraint arrows can be configured using the context menu, as shown in Figure
7-17
. Or you
can right-click the arrow and select Edit from the context menu to access the Precedence Constraint Editor
(Figure
7-18
).
Figure 7-18.
The Precedence Constraint Editor dialog
In the Precedence Constraint Editor, you can set the arrow to configure expression values as well as
constraint operation values, such as Success, Completion, and Failure.
Expressions values always evaluate a true or false Boolean value, but they can be combined with the
constraint values to give you a rather elaborate logic. Figure
7-19
shows an example of using both expressions
and constraints.
The Evaluation Operation dropdown box allows you to set the precedence constraint to consider the
following combinations:
•
Constraint
•
Expression
•
Constraint and Expression
•
Constraint or Expression
These combinations let you fine-tune the constraint process. In Figure
7-19
, if the expression value
evaluates the
@RowCount
variable as equal to zero or the constraint evaluates that the connected task has failed its
execution, then at least one of these conditions is met, and SSIS passes control onto the next task for processing.
