场景：我希望同时从N个表中拿出数据并组合到一起，然后按时间倒序排列。（用户动态）
表1 co： cid name linkid type date content
表2 to： tid name date title content
表3 wo wid name date title content
表1中的linkid可能是tid或者wid，由type来决定。
请问这样的语句要怎么写？PS：最好能将效率问题也考虑进去...我曾用UNION写了一个，效率奇差...
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场景：我希望同时从N个表中拿出数据并组合到一起，然后按时间倒序排列。（用户动态）
表1 co： cid name linkid type date content
表2 to： tid name date title content
表3 wo wid name date title content
表1中的linkid可能是tid或者wid，由type来决定。
请问这样的语句要怎么写？PS：最好能将效率问题也考虑进去...我曾用UNION写了一个，效率奇差...
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What is the significance of the session_start() function?May 03, 2025 am 12:18 AMsession_start()iscrucialinPHPformanagingusersessions.1)Itinitiatesanewsessionifnoneexists,2)resumesanexistingsession,and3)setsasessioncookieforcontinuityacrossrequests,enablingapplicationslikeuserauthenticationandpersonalizedcontent.
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