站内信数据表，如何取出某个用户最近 10 个联系人？

[WildCat]

我的站内信的数据表大约有如下字段：

• id
• receiver_id
• sender_id
• is_read
• content
• created_at

eg. 如何取出 receiver_id = 1 的最近10个 sender_id ?

[xenme]

不是特别熟悉，大概应该这样：
select * from table where receiver_id=1 order by creted_at desc limit 10

[yangqi]

SELECT sender_id FROM 表 WHERE receiver_id=1 ORDER BY created_at DESC LIMIT 10;

[xenme]

可能sender有重复
select distinct sender_id,created_at from table where receiver_id=1 order by creted_at desc limit 10

[heaton_nobu]

我只想问问为什么不用主键id，而非要用created_at，难道不是新建的id就大吗

[WildCat]

@xenme 感谢。已经找到：

http://guides.rubyonrails.org/active_record_querying.html
```ruby
query = Client.select(:name).distinct
# => Returns unique names

query.distinct(false)
# => Returns all names, even if there are duplicates
```

结贴。

[staticor]

用groupby 之类的对sender_id 去个重?

[msg7086]

where.distinct.first 10