查詢聯合，如果搜索結果小於10，則按日期從數據庫順序中填充其他

Question

我想進行mysql聯合搜索。 我的目的是：我的總成績必須是10。

• 如果搜索結果大於10，則返回的數據全部來自搜索結果。
• 如果搜索結果小於10，則返回的前幾個數據來自搜索結果，然后按日期從數據庫順序中獲取其余結果。

更清楚地說：如果客戶搜索“今天”，則我的數據庫僅返回7個包含“今天”的結果，然后從數據庫ORDER BY日期中添加另外3個結果。 這樣一來，總結果為10個項目。

另一個目的：另外3個結果不是與搜索匹配的7個結果的重復。 我認為UNION或UNION DISTINCT可以完成這項工作，對嗎？

那么，我該如何進行查詢？

PS：我的代碼將確定結果順序，但是我需要第一個select始終位於第二個select

(SELECT * FROM table WHERE title like %$searchword% limit 0,10 ORDER BY date)
UNION
(SELECT * FROM table limit 0,10 ORDER BY date)
limit 0,10 ORDER BY date

Answer 1

如果您始終想要10個結果：

SELECT 
    IF(m.id,1,0) AS has_match,
    t.*
FROM 
    `table` t
    LEFT JOIN `table` m ON m.id = t.id AND m.title LIKE '%$searchword%'
GROUP BY t.id
ORDER BY has_match DESC, date
LIMIT 10

經過測試：

mysql> select * from `table`;
+----+------------------------+---------------------+
| id | title                  | date                |
+----+------------------------+---------------------+
|  1 | test 1                 | 2011-11-06 10:27:08 |
|  2 | test 2 match           | 2011-11-06 10:27:14 |
|  3 | 3 match this too       | 2011-11-06 10:27:23 |
|  4 | title does NOT         | 2011-11-06 10:27:44 |
|  5 | Another matching title | 2011-11-06 10:27:55 |
|  6 | this does not either   | 2011-11-06 10:29:22 |
|  7 | Do not put this first  | 2011-11-06 10:29:37 |
|  8 | Is this number 8?      | 2011-11-06 10:29:57 |
|  9 | The 9th is a match     | 2011-11-06 10:30:07 |
| 10 | 10th does not          | 2011-11-06 10:30:20 |
| 11 | 11th IS a match too!   | 2011-11-06 10:30:37 |
| 12 | 12th gets ignored?     | 2011-11-06 10:30:49 |
+----+------------------------+---------------------+
12 rows in set (0.00 sec)

mysql> SELECT IF(m.id,1,0) AS has_match, t.* FROM `table` t LEFT JOIN `table` m ON m.id = t.id AND m.title LIKE '%match%' GROUP BY t.id ORDER BY has_match DESC, date LIMIT 10;
+-----------+----+------------------------+---------------------+
| has_match | id | title                  | date                |
+-----------+----+------------------------+---------------------+
|         1 |  2 | test 2 match           | 2011-11-06 10:27:14 |
|         1 |  3 | 3 match this too       | 2011-11-06 10:27:23 |
|         1 |  5 | Another matching title | 2011-11-06 10:27:55 |
|         1 |  9 | The 9th is a match     | 2011-11-06 10:30:07 |
|         1 | 11 | 11th IS a match too!   | 2011-11-06 10:30:37 |
|         0 |  1 | test 1                 | 2011-11-06 10:27:08 |
|         0 |  4 | title does NOT         | 2011-11-06 10:27:44 |
|         0 |  6 | this does not either   | 2011-11-06 10:29:22 |
|         0 |  7 | Do not put this first  | 2011-11-06 10:29:37 |
|         0 |  8 | Is this number 8?      | 2011-11-06 10:29:57 |
+-----------+----+------------------------+---------------------+
10 rows in set (0.00 sec)