Question

我希望合并两个具有不同ORDER BY

的查询

然而另一个查询的行为并不符合它的ORDER BY

我不知道是什么导致了这个bug，但它在我的本地文件中工作正常。但是当我在实时网站上启动时，第二个查询的行为效果不佳。

问题出现在sub-query table2上它应该按starting_date descending显示所有记录顺序，但查询不会那样排序......我不知道是什么造成了这种情况。

提前致谢

这是我的mysql查询。

 SELECT * FROM (
            SELECT 
            events.event_id,
            events.event_name_en,
            events.event_name_ch,
            events.event_description_en,
            events.event_description_ch,
            events.ref,
            events.start_date,
            events.end_date,
            events.venue_id,
            events.organizers_id,
            events.website,
            events.payment_method,
            events.visitors,
            events.display,
            events.booking_form,
            events.map,
            events.lmap,
            events.insurance_offered,
            events.masterhead_img,
            events.icon_img,
            events.event_token,
            events.added_by as event_added_by,
            events.added_date as event_added_date,
            events.updated_by,
            events.updated_date,
            events.active,
            events.allow_ond,
            events.allow_ond_reg,
            events.terms_p,
            events.cancel_p,
            events.no_show_p,
            events.refund_p,
            events.official_desc,
            events.supporting_desc,
            events.participating_desc,
            events.official_title,
            events.supporting_title,
            events.participating_title,
            events.order_number,
            venue.venue_en,
            venue.venue_ch,
            venue.added_by as venue_added_by,
            venue.added_date as venue_added_date,
            venue.updated_by as venue_updated_by,
            venue.updated_date as venue_updated_date,
            countries.country_id,
            countries.country_code,
            countries.country_name

            FROM 
            events 
            INNER JOIN venue
            ON venue.venue_id=events.venue_id
            INNER JOIN countries
            ON countries.country_id=events.country_id
            WHERE events.display = '1' AND events.order_number != ''
            AND events.active = '1' 
            ORDER BY events.order_number ASC) as table1

            UNION ALL

            SELECT * FROM (SELECT 
            events.event_id,
            events.event_name_en,
            events.event_name_ch,
            events.event_description_en,
            events.event_description_ch,
            events.ref,
            events.start_date,
            events.end_date,
            events.venue_id,
            events.organizers_id,
            events.website,
            events.payment_method,
            events.visitors,
            events.display,
            events.booking_form,
            events.map,
            events.lmap,
            events.insurance_offered,
            events.masterhead_img,
            events.icon_img,
            events.event_token,
            events.added_by as event_added_by,
            events.added_date as event_added_date,
            events.updated_by,
            events.updated_date,
            events.active,
            events.allow_ond,
            events.allow_ond_reg,
            events.terms_p,
            events.cancel_p,
            events.no_show_p,
            events.refund_p,
            events.official_desc,
            events.supporting_desc,
            events.participating_desc,
            events.official_title,
            events.supporting_title,
            events.participating_title,
            events.order_number,
            venue.venue_en,
            venue.venue_ch,
            venue.added_by as venue_added_by,
            venue.added_date as venue_added_date,
            venue.updated_by as venue_updated_by,
            venue.updated_date as venue_updated_date,
            countries.country_id,
            countries.country_code,
            countries.country_name

            FROM 
            events 
            INNER JOIN venue
            ON venue.venue_id=events.venue_id
            INNER JOIN countries
            ON countries.country_id=events.country_id
            WHERE events.display = '1' AND events.order_number = ''
            AND events.active = '1' 
            ORDER BY events.start_date DESC) as table2

结果：

前两排很好。 table1 sub-query

的结果

但是当你看第三行等等时...... starting_date desc的顺序效果不好......第三行应该是world engineer blah.....

Answer 1

来自MySQL手册页

http://dev.mysql.com/doc/refman/5.7/en/union.html

但是，对单个SELECT语句使用ORDER BY并不意味着行在最终结果中出现的顺序，因为UNION默认生成一组无序行。因此，在此上下文中使用ORDER BY通常与LIMIT结合使用，因此它用于确定要为SELECT检索的所选行的子集，即使它不一定影响这些行的顺序。最终的UNION结果。如果在SELECT中没有LIMIT出现ORDER BY，它会被优化掉，因为它无论如何都不会产生任何影响。

我认为你可以通过玩ORDER BY子句来做你想做的事： -

SELECT events.event_id,
        events.event_name_en,
        events.event_name_ch,
        events.event_description_en,
        events.event_description_ch,
        events.ref,
        events.start_date,
        events.end_date,
        events.venue_id,
        events.organizers_id,
        events.website,
        events.payment_method,
        events.visitors,
        events.display,
        events.booking_form,
        events.map,
        events.lmap,
        events.insurance_offered,
        events.masterhead_img,
        events.icon_img,
        events.event_token,
        events.added_by as event_added_by,
        events.added_date as event_added_date,
        events.updated_by,
        events.updated_date,
        events.active,
        events.allow_ond,
        events.allow_ond_reg,
        events.terms_p,
        events.cancel_p,
        events.no_show_p,
        events.refund_p,
        events.official_desc,
        events.supporting_desc,
        events.participating_desc,
        events.official_title,
        events.supporting_title,
        events.participating_title,
        events.order_number,
        venue.venue_en,
        venue.venue_ch,
        venue.added_by as venue_added_by,
        venue.added_date as venue_added_date,
        venue.updated_by as venue_updated_by,
        venue.updated_date as venue_updated_date,
        countries.country_id,
        countries.country_code,
        countries.country_name
FROM events 
INNER JOIN venue ON venue.venue_id = events.venue_id
INNER JOIN countries ON countries.country_id = events.country_id
WHERE events.display = '1' 
AND events.active = '1' 
ORDER BY IF(events.order_number = '', 1, 0),
        IF(events.order_number = '', NULL, events.order_number) ASC,
        IF(events.order_number = '', events.start_date, NULL) DESC

这将首先排序来自您的第一个子查询的所有记录，然后是来自第二个子查询的所有记录。在其中，它将通过order_number ASCending排序第一个，并通过start_date DESCending排序第二个。

mysql union两个查询与order by

1 个答案: