我有两个查询来获取相同的数据，它们的执行时间大致相同。SELECTnameASprog_name,d.chap_name,d.vid_name,d.idvideoFROMprogramJOIN(SELECTnameASchap_name,chapter.idprogram,c.vid_name,c.idvideoFROMchapterJOIN(SELECTa.nameASvid_name,a.idvideo,b.idchapterFROMvideoaJOIN(SELECTidvideo,idchapter,x.idchaptervideoFROMchaptervideoJOIN(SEL