This M Code function allows you to lookup values on other rows in the same table or another table. This benefit of this process is that it allows you to use custom or unique indexes.
Create A New Blank Query
Create a new blank query in Power Query
Advanced Editor
Open the Advanced Editor
Paste the following code into a blank query named "fxLookUp":
(lookupValue as any, lookupTable as table, lookupColumnName as text, returnColumnValue as text) => let colLookup = Table.Column(lookupTable, lookupColumnName), colToReturn = Table.Column(lookupTable, returnColumnValue), lookup = List.PositionOf(colLookup, lookupValue, 0), Result = if lookup >=0 then colToReturn{lookup} else "Not found" in Result
Custom Column
Within your other Power Query process, create a new Custom Column and paste a column expression similar to below:
fxLookUp([Your Lookup Value],#"Changed Type","Your Index Column","Your Value Column")
The second index (#"Changed Type") being your previous Power Query Step Name