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Mysql仅在倒数第二个id上左连接_Mysql_Left Join - Fatal编程技术网
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Mysql仅在倒数第二个id上左连接

mysql

Mysql仅在倒数第二个id上左连接,mysql,left-join,Mysql,Left Join,我有一个查询试图求和时间： SELECT t1.id, t1.number, t1.time - COALESCE(SUM(t2.time), 0) time FROM times t1 LEFT JOIN times t2 ON t1.number = t2.number AND t2.id < t1.id GROUP BY t1.id, t1.number, t1.time 它工作得很好，但我只需要在子句中用左连接条件的倒数第二个id求和（t2.id

我有一个查询试图求和时间：

SELECT t1.id, t1.number, t1.time - COALESCE(SUM(t2.time), 0) time FROM times t1 
LEFT JOIN times t2 ON t1.number = t2.number AND t2.id < t1.id
GROUP BY t1.id, t1.number, t1.time
它工作得很好，但我只需要在子句中用左连接条件的倒数第二个id求和（
t2.id
）。

用于选择倒数第二个id

SELECT t1.id, t1.number, t1.time - COALESCE(SUM(t2.time), 0) time FROM times t1 
LEFT JOIN times t2 ON t1.number = t2.number 
AND t2.id = (select id from times order by id desc limit 1,1)
GROUP BY t1.id, t1.number, t1.time
您能发布现有数据和预期输出吗？ 
SELECT t1.id, t1.number, t1.time - COALESCE(SUM(t2.time), 0) time FROM times t1 
LEFT JOIN times t2 ON t1.number = t2.number 
AND t2.id = (select id from times order by id desc limit 1,1)
GROUP BY t1.id, t1.number, t1.time