Why we need to use unconnected transformation?

Question

In unconnected lookup, what are the other transformations that can be used in place of that expression transformation?

Answer 1

Unconnected Look Up Transformation: Unconnected lookup is generally used when the result of a query is a single column. More importantly, if it returns values like that indicate “Does the record exist”, “what’s the value of this column” and so. It can return only one input , but it is reusable and can save you a lot of effort in some cases where it’s applicable.