php - mySQL 中 FOUND_ROWS() 的错误结果

Question

我总共有 6 行。当我进行查询时(比如 SELECT * from table)并且我有

• LIMIT 3 => FOUND_ROWS() 给出 3 => 检索到 3 行
• LIMIT 1, 3 => FOUND_ROWS() 给出 4 => 检索到 3 行
• LIMIT 2, 3 => FOUND_ROWS() 给出 5 => 检索到 3 行
• LIMIT 3, 3 => FOUND_ROWS() 给出 6 => 检索到 3 行
• LIMIT 4, 3 => FOUND_ROWS() 给出 6 => 检索到 2 行

知道这种奇怪行为的原因是什么吗？

SQL 查询

SELECT `places`.*, `category`.*, COUNT(places_reviews.place_id) AS num_reviews, (places_popularity.rating_1 + 2*places_popularity.rating_2 + 3*places_popularity.rating_3 + 4*places_popularity.rating_4 + 5*places_popularity.rating_5)/(places_popularity.rating_1 + places_popularity.rating_2 + places_popularity.rating_3 + places_popularity.rating_4 + places_popularity.rating_5) AS average_rating, FOUND_ROWS() AS num_rows FROM (`places`) JOIN `category` ON `places`.`category_id` = `category`.`category_id` LEFT JOIN `places_reviews` ON `places_reviews`.`place_id` = `places`.`id` LEFT JOIN `places_popularity` ON `places_popularity`.`place_id` = `places`.`id` WHERE `places`.`category_id` = 1 AND `places`.`name` LIKE '%%' GROUP BY `places`.`id` ORDER BY `id` desc LIMIT 3

或者在一个 block 中:

SELECT `places`.*, `category`.*, 
COUNT(places_reviews.place_id) AS num_reviews, 
(places_popularity.rating_1 + 2*places_popularity.rating_2 + 3*places_popularity.rating_3 + 4*places_popularity.rating_4 + 5*places_popularity.rating_5)/(places_popularity.rating_1 + places_popularity.rating_2 + places_popularity.rating_3 + places_popularity.rating_4 + places_popularity.rating_5) AS average_rating, FOUND_ROWS() AS num_rows FROM (`places`) 
JOIN `category` ON `places`.`category_id` = `category`.`category_id` 
LEFT JOIN `places_reviews` ON `places_reviews`.`place_id` = `places`.`id` 
LEFT JOIN `places_popularity` ON `places_popularity`.`place_id` = `places`.`id` 
WHERE `places`.`category_id` = 1 
    AND `places`.`name` LIKE '%%' 
GROUP BY `places`.`id` 
ORDER BY `id` desc LIMIT 3

Answer 1

编辑:

这就是您要找的: http://dev.mysql.com/doc/refman/5.0/en/information-functions.html#function_found-rows

所以在你的查询中:

选择 sql_calc_found_rows .....