Question

我有一个存储过程，根据用户可以选择要搜索的多个位置来查找用户的首选项。因此，对于每个位置，查询需要在该区域内查找结果。目前，该过程仅返回1个结果。此外，我希望能够实现某种排名系统，以便将结果排序为一个组合的Feed。我意识到，如果我使用while循环，那将按位置对结果进行分组，这是我不想要的。重构此过程的最佳方法是什么，以便对3个查询的结果进行网格划分，并允许我灵活地对结果进行排序？

DELIMITER $$

    DROP PROCEDURE IF EXISTS `geodist` $$
    CREATE PROCEDURE geodist (IN userid INT) BEGIN
    DECLARE mylon DOUBLE;  DECLARE mylat DOUBLE;
    DECLARE lon1 FLOAT;  DECLARE lon2 FLOAT;
    DECLARE lat1 FLOAT; DECLARE lat2 FLOAT;
    DECLARE dist INT;
    DECLARE no_more_locations INT; DECLARE l_location_count INT;

    -- get the original lon and lat for the userid
    DECLARE location_cursor CURSOR FOR
        SELECT geo_lat, geo_long, distance
        FROM activity_location_preferences
        INNER JOIN activity_preferences ON activity_location_preferences.preference_id = activity_preferences.id
        WHERE activity_preferences.user_id = userid
        ORDER BY activity_preferences.id ASC
        LIMIT 3;

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET no_more_locations = 1;

    SET no_more_locations = 0;
    OPEN location_cursor;
    location_loop:WHILE(no_more_locations = 0) DO
        FETCH location_cursor INTO mylat, mylon, dist;
        IF no_more_locations = 1 THEN
            LEAVE location_loop;
        END IF;
        SET l_location_count = l_location_count+1;

        -- calculate lon and lat for the rectangle:
        SET lon1 = mylon - dist / abs(cos(radians(mylat)) * 69);
        SET lon2 = mylon + dist / abs(cos(radians(mylat)) * 69);
        SET lat1 = mylat - (dist / 69);
        SET lat2 = mylat + (dist / 69);

        -- run the query:
        SELECT `id`, `user_id`, `activity`, `geo_lat`, `geo_long`, `data`, `date_created`,  
        7912 * ASIN(SQRT(POWER(SIN((mylat - activity_logs.geo_lat) * pi()/180 / 2), 2) +  
        COS(mylat * pi()/180) *  COS(activity_logs.geo_lat * pi()/180) *  POWER(SIN((mylon - activity_logs.geo_long) * pi()/180 / 2), 2)  )) as distance
        FROM activity_logs
        WHERE 1
        AND activity_logs.geo_long BETWEEN lon1 AND lon2 
        AND activity_logs.geo_lat BETWEEN lat1 AND lat2
        HAVING distance < dist ORDER BY date_created DESC LIMIT 100;

    END WHILE location_loop;
    CLOSE location_cursor;
    SET no_more_locations = 0;

END $$

DELIMITER ;

Answer 1

最简单的方法是创建一个临时表来存储3个结果，然后从临时表中查询3个结果作为该过程的最终结果。

另一种方法是使用子查询将所有查询重写为一个查询，如果我从头开始写这个，我可能会自己这样做，因为它比使用临时表更快。

结合MySQL存储过程的结果

1 个答案: