MySQL子查詢分組依據

Question

我有一個查詢，該查詢根據一個人的ID（運動員ID）顯示比賽結果列表。 我查詢了數據庫，以便按時間（性能）和事件（eventid）的順序列出人員的種族，但是我正努力將其設置為子查詢，以便以后可以對結果進行分組以使我得到最快的結果每個eventid的性能。 這是我到目前為止的內容：

$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");

這可以正常工作，並以正確的順序顯示所有相關條目。 然后，我嘗試將其轉到子查詢中，以便隨后可以使用GROUP BY，但沒有成功。 這是我嘗試使用的地方：

$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");

但是，這給我一個錯誤，它指出：'group statement'中的未知列't1.eventid'

任何幫助是極大的贊賞

Answer 1

您尚未在子查詢中選擇eventid 。 如果不存在，如何分組？

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

這是因為您在子查詢中沒有該列，請嘗試在子選擇中添加該列：

$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");