"按"分组"计数"的结果？

Question

这个查询

Message.where("message_type = ?", "incoming").group("sender_number").count

会给我一个哈希值.

OrderedHash {"1234"=>21, "2345"=>11, "3456"=>63, "4568"=>100}

现在我想按每组的数量排序.我该如何在查询中执行此操作.

Answer 1

最简单的方法是在原始查询中添加一个order子句.如果为count方法指定一个特定字段,它将生成一个名为count_ {column}的输出列,该列可以在通过添加订单调用生成的sql中使用:

Message.where('message_type = ?','incoming')
       .group('sender_number')
       .order('count_id asc').count('id')

Answer 2

当我尝试这个时,rails给了我这个错误

SQLite3::SQLException: no such column: count_id: SELECT  COUNT(*) AS count_all, state AS state FROM "ideas"  GROUP BY state ORDER BY count_id desc LIMIT 3

请注意,它表示SELECT ... AS count_all

所以我从@ Simon的答案中更新了查询,看起来像这样,它对我有用

.order('count_all desc')