Question: What is the percentage of all the trains with at least 4 cars? List the directions of the said trains.
SQL: SELECT CAST(COUNT(CASE WHEN T2.trailPosi >= 4 THEN T1.id ELSE NULL END) AS REAL) * 100 / COUNT(T1.id) FROM trains AS T1 INNER JOIN ( SELECT train_id, MAX(position) AS trailPosi FROM cars GROUP BY train_id ) AS T2 ON T1.id = T2.train_id UNION ALL SELECT T1.direction FROM trains AS T1 INNER JOIN ( SELECT train_id, MAX(position) AS trailPosi FROM cars t GROUP BY train_id ) AS T2 ON T1.id = T2.train_id AND T2.trailPosi >= 4