Only 1 minute after asking the question I found my answer. In the order by clause use case to make nulls have a higher value than anything else:
ORDER BY (CASE WHEN districts.id IS NULL then 1 ELSE 0 END),districts.name, schools.name;
Only 1 minute after asking the question I found my answer. In the order by clause use case to make nulls have a higher value than anything else:
ORDER BY (CASE WHEN districts.id IS NULL then 1 ELSE 0 END),districts.name, schools.name;