In the Expression transformation, configure the expression to aggregate for each row that the mapping processes.
Select the Expression transformation in the mapping editor to view the transformation properties.
Open the
Mapping Outputs
view.
Create a mapping outputs expression.
The Developer tool creates an output expression with an output name that matches one of the mapping outputs you created at the mapping level. If you have more than one mapping output in the mapping properties, select the appropriate mapping output name to use.
Click the
Expression
column to enter an expression in the
Expression Editor
.
The expression can contain just a port name or it can contain functions, ports, and parameters. If the expression contains parameters, the parameter values can be set in a parameter file or parameter set.
Click
Validate
to verify that the expression is valid.
Click
OK
to save the expression.
The expression appears in the
Expression
column for the mapping output expression.
Click
File
Save
to save the Expression transformation.
The following image shows the saved mapping output expression. The expression uses only the port 'ID' to calculate the mapping output.