使用具有不同随机子查询结果的 GroupBy 在 MySQL 中随机选择子查询 [英] Randomizing Select SubQuery in MySQL using GroupBy with different random SubQuery results

问题描述

如何为同一国家/地区显示不同的members.name，目前如果为同一国家/地区显示相同的members.name，但在每次查询执行时不同.

How to show different members.name for the same country, currently if shows the same members.name for the same country, but different one at each query execution.

基于上一个问题:使用GroupBy时在MySQL中随机选择子查询

查询:

 SELECT 
        country.guid,
        country.Name AS 'country name',
        country.Area_id,
        country_cities.guid,
        country_cities.name AS 'city name',
        country_streets.guid,
        country_streets.name AS 'country streets',
        memebers.name.guid,
        memebers.name AS 'street members'
    FROM
        country
            JOIN
        (SELECT 
            RAND() as seed, country_id, guid, name
        FROM
            street_members GROUP BY seed, name, guid,country_id ORDER BY seed) memebers ON memebers.country_id = country.id
            JOIN
        country_cities ON country_cities.country_id = country.id
            JOIN
        country_streets ON country_streets.city_id = country_cities.id
    GROUP BY country.guid , country_cities.guid , country_streets.guid
    ORDER BY RAND()
    LIMIT 0 , 100

推荐答案

如上一个问题所示，country_streets 和 street_members 之间没有直接链接，所以我只看到以下解决方案:

As seen in a previous question, you don't have a direct link between country_streets and street_members, so I only see the following solution :

SELECT 
        country.guid,
        country.Name AS 'country name',
        country.Area_id,
        country_cities.guid,
        country_cities.name AS 'city name',
        country_streets.guid,
        country_streets.name AS 'country streets',
        memebers.name.guid,
        memebers.name AS 'street members'
    FROM
        country
            JOIN
        country_cities ON country_cities.country_id = country.id
            JOIN
        country_streets ON country_streets.city_id = country_cities.id
            JOIN
        (SELECT 
            RAND() as seed, country_id, city_id, cs.id as streets_id, guid, name
         FROM
            street_members sm 
            JOIN country_cities cc ON sm.country_id = cc.country_id 
            JOIN country_streets cs ON cs.city_id = cc.country_id 
         GROUP BY seed, name, guid,country_id,city_id,streets_id ORDER BY seed
        ) memebers ON memebers.streets_id=country_streets.id
    GROUP BY country.guid , country_cities.guid , country_streets.guid
    ORDER BY RAND()
    LIMIT 0 , 100

同样，它没有在您的特定数据库上进行测试(当然可以在这里和那里改进)，但您明白了.

Again it's not tested on your specific database (and could surely be improved here and there) but you get the idea.

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