1.from tab1 t1,where t1.city in (select t2.city from tab2 where safety_score = 1) select capitaincome, t1.city, safety_score tab1 t2
where t1.city in (select city from tab2 where s
我尝试在Rails 3的Arel和/或Active Record中嵌套SELECT查询,以生成以下SQL语句。SELECT sorted.* FROM (SELECT * FROM points ORDER BY points.timestamp DESC) AS sorted GROUP BY sorted.client_id可以通过执行以下操作创建子查询的别名sorted = points.order(