Exclude rows with NaN results

I have a Druid SQL query that looks like this:

{“query”:“SELECT clientId, sum(orderDiscount)/count(orderID) as avg_discount_per_order FROM sometable GROUP BY clientId”}

This is my response:

        "clientId": "abc",
        "avg_discount_per_order": "NaN"
        "clientId": "xyz",
        "avg_discount_per_order": 10

Is there anything I can do to exclude results with avg_discount_per_order = 'NaN' ?

Thank You!

You could probably do it with a HAVING filter.