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我有3個表:P,P2L,LSQL - 與許多返回最大日至多個表
p - p_id;
p2l - p_id, l_id
l - l_id, date
我如何獲得最大的(日期)每個的p_id?
這個查詢是否正確?
SELECT plot_id, max(l.date) as l_maxDate
FROM p2l
LEFT JOIN l ON p2l.l_id = l.l_id
Group by p_id
SELECT plot_id, maxDate.maxLDate,
FROM p2l
INNER JOIN
(SELECT l_id, MAX(date) AS maxLDate
FROM l
GROUP BY l_id) maxDate
ON maxDate.l_id = p2l.l_id
GROUP BY p_id
您最大日期指的是什麼最新的日期? – 2013-02-20 08:43:30