Question

我使用 MYSQL ;

有3个表关系

首先作为车手表示例：

bib   |   series_id    | point
 202         3             200
 219         3             140
 202         2             200
 219         2             110
 10          1             90

第二个例子为系列表：

series_id   |   series_no  |   season_id
     1            1                2
     2            2                1
     3            1                1

示例第三个作为季节表：

 season_id   |   year
     1            2015
     2            2016

如何正确指出GROUP_CONCAT？我试着这样做

SELECT riders.bib, seasons.year, GROUP_CONCAT(DISTINCT riders.point ORDER BY series.series_no DESC) AS seriPoint 
    FROM series, riders, seasons 
    GROUP BY riders.bib

当我使用bib: 202 is 200 and bib: 219 is 140,110输出时，我正在为DISTINCT获取输出seriPoint。但是当我没有使用DISTINCT获取bib: 202 is 200,200,200,200 and bib: 219 is 140,110,140,110的输出seriPoint时。我想要的是为bib: 202 is 200,200 and bib: 219 is 140,110输出seriPoint。

ADD：也可以帮助添加过滤器，season_id当不同的season_id为不同的行时。

Answer 1

是的，因为您使用了DISTINCT，所以输出正确。顺便说一下，你应该改变你的查询以使用正确的JOINS

SELECT riders.bib, 
seasons.year, 
GROUP_CONCAT(DISTINCT riders.point ORDER BY series.series_no DESC) AS seriPoint 
FROM riders
JOIN series ON series.series_id = riders.series_id
JOIN seasons ON series.season_id = seasons.season_id
GROUP BY riders.bib;

（或）您可以先获得分组，然后执行

之类的连接

select seasons.year, xx.bib, xx.seriPoint
FROM series
JOIN (  
select series_id, bib 
group_concat(point) as seriPoint 
from riders
group by bib ) xx ON series.series_id = xx.series_id
JOIN seasons ON series.season_id = seasons.season_id
order by xx.seriPoint;

如何使用distinct正确的group_concat - MYSQL

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