Mysql的查詢 - 對於每一日期，最多3個DATAS

Question

這是我的數據庫表中的數據，{我一直保持着只有一個表}

我需要從每個起始日期獲取最多3個數據，

給我任何的想法來開發查詢,,

Answer 1

SELECT a.* 
FROM Table1 a 
INNER JOIN Table1 b ON a.start_date = b.start_date AND a.event_id <= b.event_id 
GROUP BY a.event_id,a.start_date 
HAVING COUNT(*) <= 3 
ORDER BY a.start_date 

Answer 2

我可以建議你這個查詢 -

SELECT * FROM (
    SELECT t1.*, COUNT(*) pos FROM table t1 
    LEFT JOIN table t2 
     ON t2.start_date = t1.start_date AND t2.event_id <= t1.event_id 
    GROUP BY 
    t1.start_date AND t1.event_id 
) t 
WHERE 
    pos <= 3; 

它選擇3行，最小event_id在start_date組中。