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推薦的方法做尋呼MySQL時，計數事項

2011-04-20 35 views
4

我有一個MySQL表建議這樣推薦的方法做尋呼MySQL時，計數事項

id:int 
user_id:int 
item_id:int

，我想實現分頁爲最建議項目深受用戶歡迎。假設每一頁大小是9，所以我試圖

select count(id) as total,item_id from suggestions group by item_id order by total desc limit 9;

簡單地適用於在第一頁和第二在頁面返回

+-------+---------+ 
| total | item_id | 
+-------+---------+ 
|  6 |  4 | 
|  6 |  8 | 
|  6 |  16 | 
|  5 |  5 | 
|  5 |  6 | 
|  5 |  1 | 
|  3 |  17 | 
|  2 |  3 | 
|  2 |  7 | 
+-------+---------+

我想顯示從總的結果= 2和ITEM_ID = 2。在SQL服務器中，我可以使用Row_number()方法爲分頁行編號。但我在MySQL中找不到這樣的東西。

是mysql的新手，有人能幫我一下。

見附件下面

+----+---------+---------+---------------------+---------------------+ 
| id | user_id | item_id | created_at   | updated_at   | 
+----+---------+---------+---------------------+---------------------+ 
| 1 |  4 |  1 | 2011-04-18 05:21:08 | 2011-04-18 05:21:08 | 
| 6 |  5 |  2 | 2011-04-18 07:28:25 | 2011-04-18 07:28:25 | 
| 8 |  5 |  3 | 2011-04-18 08:10:46 | 2011-04-18 08:10:46 | 
| 9 |  4 |  4 | 2011-04-18 12:58:17 | 2011-04-18 12:58:17 | 
| 10 |  4 |  5 | 2011-04-18 13:24:59 | 2011-04-18 13:24:59 | 
| 11 |  4 |  6 | 2011-04-18 13:28:28 | 2011-04-18 13:28:28 | 
| 12 |  4 |  7 | 2011-04-18 13:30:20 | 2011-04-18 13:30:20 | 
| 13 |  8 |  5 | 2011-04-18 13:42:30 | 2011-04-18 13:42:30 | 
| 14 |  8 |  6 | 2011-04-18 13:42:44 | 2011-04-18 13:42:44 | 
| 15 |  8 |  4 | 2011-04-18 13:42:52 | 2011-04-18 13:42:52 | 
| 16 |  9 |  5 | 2011-04-18 13:44:34 | 2011-04-18 13:44:34 | 
| 17 |  9 |  6 | 2011-04-18 13:45:23 | 2011-04-18 13:45:23 | 
| 18 |  9 |  7 | 2011-04-18 13:46:28 | 2011-04-18 13:46:28 | 
| 19 |  9 |  1 | 2011-04-18 13:46:29 | 2011-04-18 13:46:29 | 
| 20 |  4 |  8 | 2011-04-18 13:58:38 | 2011-04-18 13:58:38 | 
| 21 |  8 |  8 | 2011-04-18 13:59:39 | 2011-04-18 13:59:39 | 
| 22 |  9 |  8 | 2011-04-18 14:00:47 | 2011-04-18 14:00:47 | 
| 23 |  8 |  1 | 2011-04-18 14:03:58 | 2011-04-18 14:03:58 | 
| 24 |  4 |  9 | 2011-04-19 10:24:38 | 2011-04-19 10:24:38 | 
| 25 |  4 |  10 | 2011-04-19 10:54:13 | 2011-04-19 10:54:13 | 
| 26 |  4 |  11 | 2011-04-19 10:57:10 | 2011-04-19 10:57:10 | 
| 27 |  12 |  8 | 2011-04-19 11:33:02 | 2011-04-19 11:33:02 | 
| 28 |  12 |  4 | 2011-04-19 11:33:18 | 2011-04-19 11:33:18 | 
| 29 |  12 |  1 | 2011-04-19 12:07:51 | 2011-04-19 12:07:51 | 
| 30 |  12 |  6 | 2011-04-19 12:09:05 | 2011-04-19 12:09:05 | 
| 31 |  12 |  12 | 2011-04-19 13:07:35 | 2011-04-19 13:07:35 | 
| 32 |  9 |  13 | 2011-04-19 13:29:17 | 2011-04-19 13:29:17 | 
| 33 |  9 |  14 | 2011-04-19 13:45:56 | 2011-04-19 13:45:56 | 
| 34 |  9 |  15 | 2011-04-19 13:49:08 | 2011-04-19 13:49:08 | 
| 35 |  14 |  16 | 2011-04-19 16:47:28 | 2011-04-19 16:47:28 | 
| 36 |  4 |  16 | 2011-04-19 16:49:46 | 2011-04-19 16:49:46 | 
| 37 |  13 |  16 | 2011-04-19 16:50:29 | 2011-04-19 16:50:29 | 
| 38 |  15 |  5 | 2011-04-19 16:53:55 | 2011-04-19 16:53:55 | 
| 39 |  15 |  16 | 2011-04-19 16:54:15 | 2011-04-19 16:54:15 | 
| 40 |  15 |  8 | 2011-04-19 16:54:29 | 2011-04-19 16:54:29 | 
| 41 |  15 |  4 | 2011-04-19 16:58:20 | 2011-04-19 16:58:20 | 
| 42 |  15 |  0 | 2011-04-19 16:59:21 | 2011-04-19 16:59:21 | 
| 44 |  9 |  4 | 2011-04-19 17:03:54 | 2011-04-19 17:03:54 | 
| 45 |  9 |  16 | 2011-04-19 17:03:57 | 2011-04-19 17:03:57 | 
| 46 |  13 |  8 | 2011-04-19 17:08:56 | 2011-04-19 17:08:56 | 
| 47 |  13 |  6 | 2011-04-19 17:08:58 | 2011-04-19 17:08:58 | 
| 48 |  13 |  17 | 2011-04-19 17:10:26 | 2011-04-19 17:10:26 | 
| 49 |  18 |  16 | 2011-04-19 17:15:49 | 2011-04-19 17:15:49 | 
| 50 |  18 |  4 | 2011-04-19 17:15:52 | 2011-04-19 17:15:52 | 
| 51 |  18 |  1 | 2011-04-19 17:15:53 | 2011-04-19 17:15:53 | 
| 52 |  18 |  5 | 2011-04-19 17:15:54 | 2011-04-19 17:15:54 | 
| 53 |  18 |  17 | 2011-04-19 17:15:57 | 2011-04-19 17:15:57 | 
| 54 |  19 |  17 | 2011-04-19 17:21:45 | 2011-04-19 17:21:45 | 
| 55 |  19 |  18 | 2011-04-19 17:22:28 | 2011-04-19 17:22:28 | 
| 56 |  22 |  19 | 2011-04-19 17:35:40 | 2011-04-19 17:35:40 | 
| 57 |  26 |  20 | 2011-04-19 17:46:00 | 2011-04-19 17:46:00 | 
| 58 |  26 |  21 | 2011-04-19 17:51:51 | 2011-04-19 17:51:51 | 
| 59 |  26 |  22 | 2011-04-19 17:54:32 | 2011-04-19 17:54:32 | 
| 60 |  26 |  23 | 2011-04-19 18:11:24 | 2011-04-19 18:11:24 | 
| 61 |  26 |  24 | 2011-04-19 18:12:23 | 2011-04-19 18:12:23 | 
| 62 |  27 |  2 | 2011-04-19 18:24:38 | 2011-04-19 18:24:38 | 
| 63 |  27 |  25 | 2011-04-19 18:29:07 | 2011-04-19 18:29:07 | 
| 64 |  27 |  26 | 2011-04-19 18:31:51 | 2011-04-19 18:31:51 | 
| 65 |  27 |  3 | 2011-04-19 18:32:46 | 2011-04-19 18:32:46 | 
+----+---------+---------+---------------------+---------------------+

來源

2011-04-20 RameshVel

回答

6

樣本數據您是否嘗試過：

select count(id) as total,item_id from suggestions 
group by item_id order by total desc 
limit 9 offset 9;

來源

2011-04-20 10:34:26

+1

這是MySQL的正確答案，但是我想指出的是，對於MyISAM存儲當數以百萬計的行和偏移量很高時，這會對性能造成嚴重影響。儘管Sam的建議是正確的，但我建議您通過以下鏈接獲取有關MySQL中LIMIT OFFSET優化的深入見解 - http://explainextended.com/2011/02/11/late-row-lookups-innodb/ – 2011-04-20 10:36:12

+0

yep thats我在找什麼.. :) – RameshVel 2011-04-20 10:38:56

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