Question

我有一个查询，根据一个人的id（athleteid）显示比赛结果列表。我已经查询了数据库，以便按照时间（性能）和事件（偶数）的顺序列出人员的比赛，但是我很难将其设置为子查询，以便我可以将结果分组以便让我最快每个晚上的表现。这就是我到目前为止所做的：

$id = $_GET['id'];
$query = sprintf("SELECT events.eventcode, meetings.meetingid, meetings.meetingname, meetings.location, meetings.meetingdate, DATE_FORMAT(meetings.meetingdate,'%%d %%b %%Y') AS date, results.performance, results.unit, results.wind, agegroups.agegroup
FROM results 
JOIN athletes ON athletes.athleteid = results.athleteid
JOIN meetings ON meetings.meetingid = results.meetingid
JOIN events ON events.eventid = results.eventid
JOIN agegroups ON agegroups.agegroupid = results.agegroupid
WHERE results.athleteid='$id' AND events.eventtype = 'track' ORDER BY results.eventid asc, results.performance asc, meetings.meetingdate desc");

此工作正常，并以正确的顺序显示所有相关条目。然后我尝试将其转换为子查询，以便我可以使用GROUP BY，但没有成功。这是我试图用它的地方：

$id = $_GET['id'];
$query = sprintf("SELECT * FROM (SELECT events.eventcode, meetings.meetingid, meetings.meetingname, meetings.location, meetings.meetingdate, DATE_FORMAT(meetings.meetingdate,'%%d %%b %%Y') AS date, results.performance, results.unit, results.wind, agegroups.agegroup
FROM results 
JOIN athletes ON athletes.athleteid = results.athleteid
JOIN meetings ON meetings.meetingid = results.meetingid
JOIN events ON events.eventid = results.eventid
JOIN agegroups ON agegroups.agegroupid = results.agegroupid
WHERE results.athleteid='$id' AND events.eventtype = 'track' ORDER BY results.eventid asc, results.performance asc, meetings.meetingdate desc) AS t1
GROUP BY t1.eventid");

然而，这给了我一个错误，指出：'group statement'中的未知列't1.eventid'

非常感谢任何帮助

Answer 1

您未在子查询中选择eventid。如果不存在，你怎么能分组？

SELECT events.eventid,events.eventcode, 
meetings.meetingid, meetings.meetingname, 
meetings.location, meetings.meetingdate, 
DATE_FORMAT(meetings.meetingdate,'%%d %%b %%Y') AS date, 
results.performance, results.unit, results.wind, 
agegroups.agegroup
.......

Answer 2

这是因为您在子查询中没有该列，请尝试在子选择上添加该列：

$id = $_GET['id'];
$query = sprintf("SELECT * FROM (SELECT events.eventid, events.eventcode, meetings.meetingid, meetings.meetingname, meetings.location, meetings.meetingdate, DATE_FORMAT(meetings.meetingdate,'%%d %%b %%Y') AS date, results.performance, results.unit, results.wind, agegroups.agegroup
FROM results 
JOIN athletes ON athletes.athleteid = results.athleteid
JOIN meetings ON meetings.meetingid = results.meetingid
JOIN events ON events.eventid = results.eventid
JOIN agegroups ON agegroups.agegroupid = results.agegroupid
WHERE results.athleteid='$id' AND events.eventtype = 'track' ORDER BY results.eventid asc, results.performance asc, meetings.meetingdate desc) AS t1
GROUP BY t1.eventid");

MySQL子查询组

2 个答案: