在mysql中刪除時間戳間隔小於5秒的重複行

Question

我有一臺服務器在每次訪問時向數據庫添加多條記錄。服務器在每次訪問的2-5個記錄之間完成了它。所有的數據都是相同的期望時間戳。我想每次訪問只保留1條記錄。並刪除其他記錄。

之前：

+----+----------------------+------+--------+ 
| id |  timestamp  | user | action | 
+----+----------------------+------+--------+ 
| 1 | 01-01-01-16 03:02:05 | 5 | visit | 
| 2 | 01-01-01-16 03:02:06 | 5 | visit | 
| 3 | 01-01-01-16 03:02:05 | 6 | watch | 
| 4 | 01-01-01-16 03:02:06 | 6 | watch | 
| 5 | 01-01-01-16 03:04:05 | 9 | visit | 
| 6 | 01-01-01-16 03:04:06 | 9 | visit | 
| 7 | 01-01-01-16 03:04:07 | 9 | visit | 
| 8 | 01-01-01-16 03:04:35 | 2 | see | 
+----+----------------------+------+--------+ 

預期結果：

+----+----------------------+------+--------+ 
| id |  timestamp  | user | action | 
+----+----------------------+------+--------+ 
| 1, | 01-01-01-16 03:02:05 | 5 | visit | 
| 3, | 01-01-01-16 03:02:05 | 6 | watch | 
| 4, | 01-01-01-16 03:02:06 | 6 | watch | 
| 5, | 01-01-01-16 03:04:05 | 9 | visit | 
| 8, | 01-01-01-16 03:04:35 | 2 | see | 
+----+----------------------+------+--------+ 

換句話說：正如所看到的，線1,2是相同的。同一個用戶，並且只有一秒之間。所以我刪除線2.4，我不碰線，因爲它不是一個訪問

我有查詢的開頭：delete from table where id in(...)

Answer 1

使用join執行查詢更快

DELETE t1 FROM visit t1 
INNER JOIN visit t2 ON v1.user = v2.user 
WHERE v1.id < v2.id AND 
TIMESTAMPDIFF(SECOND, t1.timestamp, t2.timestamp) < 5 AND 
t1.action = 'visit' AND 
t2.action = 'visit' 

Answer 2

DELETE FROM visit 
     WHERE id IN (
       SELECT v2.id 
       FROM visit v1   
       JOIN visit v2 
       ON v1.id < v2.id 
       AND v1.user = v2.user      
       AND TIMESTAMPDIFF(SECOND, v1.timestamp, v2.timestamp) < 5 
       WHERE v1.action = 'visit'   
       AND v2.action = 'visit'        
       )