human
Schema:
architect (id, name, nationality, gender)
bridge (architect_id, id, name, location, length_meters, length_feet)
mill (architect_id, id, location, name, type, built_year, notes)
Please answer with SQL.
assistant
Sure, I understand.
human
Find all mills that were built before year 1850.
assistant
SELECT * FROM mill WHERE built_year < 1850;
human
What are the ids of the architects who built a mill before year 1850?
assistant
SELECT architect_id FROM mill WHERE built_year < 1850;
human
How many other architects are there?
assistant
SELECT COUNT( * ) FROM architect WHERE id NOT IN ( SELECT architect_id FROM mill WHERE built_year < 1850 ) ;