SQL SELECT ... WHERE與獨立LIMIT，OFFSET子句

Question

我有簡單的SQL查詢：

SELECT * FROM t1 
WHERE status = 1 AND user_id = ? AND some_field NOT IN (?, ?, ..., ?) 
ORDER BY createdAt DESC, rating DESC 
LIMIT 10 OFFSET 0; 

但我想沒有循環在我的PHP代碼完成對接入用戶的集合類似的查詢。看起來我需要在user_id =中使用IN子句？條件（user_id IN（？，...？））和單獨的LIMIT，OFFSET子句，用於user_id IN子句中的每個id。我知道這是不可能的，但也許存在任何解決方法而不會降低我的查詢性能？

我使用PostgreSQL 9.0.3，我假設也可以使用存儲過程來解決這個問題。

Answer 1

select * 
from (
    select *, 
     row_number() over(
      partition by user_id 
      order by createdat desc, rating desc 
     ) as rn 
    from t1 
    where 
     status = 1 and some_field not in (?, ?, ..., ?) 
     and user_id in (1,2,3) 
) s 
where rn <= 10 
order by user_id, rn 

窗口功能：

http://www.postgresql.org/docs/current/static/functions-window.html

http://www.postgresql.org/docs/current/static/sql-expressions.html#SYNTAX-WINDOW-FUNCTIONS

http://www.postgresql.org/docs/current/static/tutorial-window.html