Question

Is it possible in MySQL to do something like this:

SELECT COUNT(*) as totalcount, 
       COUNT(*) WHERE foo IS NULL as conditional_count 
  FROM baz

i.e. get two counts, one of everything, and one of things matching a WHERE clause, in a single select?

Answer 1

This would work if your database supports the CASE WHEN statement, otherwise you’ll still get the basic idea.

SELECT COUNT(*), 
       SUM(CASE WHEN FOO IS NULL THEN 1 ELSE 0 END) AS COUNT_CONDITIONAL
  FROM baz