How do I return my records grouped by NULL and NOT NULL?

Question

I have a table that has a processed_timestamp column -- if a record has been processed then that field contains the datetime it was processed, otherwise it is null.

Answer 1

In MySQL you could do something like

SELECT 
    IF(ISNULL(processed_timestamp), 'NULL', 'NOT NULL') as myfield, 
    COUNT(*) 
FROM mytable 
GROUP BY myfield