Today I Learned: collection of notes, tips and tricks and stuff I learn from day to day working with computers and technology as a developer

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Counting NULL and non-NULL values in a single query

I do not know why I had to look this up recently, it seemed like a scenario you would come across ever so often. Anyway, when you have a record set where you need to count something, where you assert that it either holds a value or the value NULL.

select sum(case when a is null then 1 else 0 end) count_nulls
     , count(a) count_not_nulls
  from table;