今天我反对一种新的查询优化问题。
我的问题是:
SELECT *
FROM sanrss
LEFT JOIN sanrum ON sanrum.sanrum___rforefide = sanrss.sanrss___rforefide AND sanrum.sanrum___rfovsnide = sanrss.sanrss___rfovsnide AND sanrum.sanrum___sanrsside = sanrss.sanrsside
LEFT JOIN sanact ON sanact.sanact___rforefide = sanrum.sanrum___rf