An unconnected Lookup transformation is a Lookup transformation that is not connected to any source, target, or transformation in the pipeline.

An unconnected Lookup transformation receives input values from the result of a :LKP expression in another transformation. The Integration Service queries the lookup source or cache based on the lookup ports and condition in the Lookup transformation and passes the returned value to the port that contains the :LKP expression. The :LKP expression can pass lookup results to an expression in another transformation.

The syntax for the lookup expression is

:LKP.lookup_transformation_name(argument, argument, ...)

The order in which you list each argument must match the order of the lookup conditions in the Lookup transformation. The Lookup transformation returns the result of the query through the Lookup transformation return port. The transformation that calls the lookup receives the lookup result value in the port that contains the :LKP expression. If the lookup query fails to return a value, the port receives a null value.

When you perform an unconnected lookup, you can perform the same lookup multiple times in a mapping. You can test the results of the lookup in another expression and filter rows based on the results.

An unconnected Lookup transformation receives input values from the result of a :LKP expression in another transformation, such as an Aggregator transformation or Expression transformation.
The Integration Service queries the lookup source or cache based on the lookup ports and condition in the Lookup transformation.
The Integration Service returns a value through the return port of the Lookup transformation.
The Integration Service passes the return value to the port that contains the :LKP expression.