Else Logic makes subqueries shorter by automatically filling in the parts of a subquery from code earlier in the query.
The first step in this process occurs when the transformer encounters the marker "*" or the table name "THIS" in a FROM statement. The transformer then looks for a previous FROM statement to replace the content of the marker with the data sources of the previous FROM. We will call this previous FROM the default data source from here on. Having a default data source and manipulating the contents of that data source is the core of Else Logic.
The reason to use both identifiers is that it was (a) easy to implement and (b) this is still an experimental method and I just want to see what people think works best. In practice I think most people will just leave out the FROM statements - as explained in the next step - but I have been wrong before.
We are still using the query from the Excel example:
"show the sales of departments selling apples"
We have shortened the original query by replacing the second mention of SalesOverview with a *. The transformer will fill this in using the code previous FROM. Click on "Generate" to see the transformation.