Null or empty values as unclassified in Pie chart

I have used this query

=case([type_of_poi] = " ", "Unclassified", [type_of_poi])

but nothing happen.

Also when used in SQL editor 'type of poi is null' then 'unclassified' (IT'S WORK)

but here we can not view the tables(my client want to see data when click on that)

please help.

Hi @varnika
Currently the Custom Expression does not handle null - this will come in 0.39.0 (in a few weeks)
Then you can do this: case(isnull([type_of_poi]), "Unclassified", [type_of_poi])
Or isempty([column]) to check for null and empty string ""

okay, but Isn't possible to view data when we create graphs in SQL editor . Please refer second graph which I have attached.

@varnika You would have to return all results remodeled via SQL, and then use that question as a base via Simple question > Saved Questions and create the Summarize and Pie chart there, then you will have drill-through available: