What are the ids, names and genders of the architects who built two bridges or one mill?
CREATE TABLE mill (architect_id VARCHAR); CREATE TABLE architect (id VARCHAR, name VARCHAR, gender VARCHAR); CREATE TABLE bridge (architect_id VARCHAR)
[SQL] SELECT T1.id, T1.name, T1.gender FROM architect AS T1 JOIN bridge AS T2 ON T1.id = T2.architect_id GROUP BY T1.id HAVING COUNT(*) = 2 UNION SELECT T1.id, T1.name, T1.gender FROM architect AS T1 JOIN mill AS T2 ON T1.id = T2.architect_id GROUP BY T1.id HAVING COUNT(*) = 1 [/SQL]