I have a query result that outputs customerID and transaction descrip.

From the same query, I actually want to only extract the transaction descript = 'refund' from all the customers. Some customers do not have the 'refund' value and if so, return as null value ex)

This is the result I get from the query:

But it should be like this:

CodePudding user response：

select CustomerID, 
       max(case when Descrip = 'refund' then Descrip else null end) as Description 
from your_table_query
group by CustomerID