Dave Blake wrote: > 3) SELECT song.*, song_artist.*, artist.* > FROM song LEFT JOIN song_artist ON song.idSong = song_artist.idSong > JOIN artist ON song_artist.idArtist = artist.idArtist > WHERE song.idSong =1 > > This ... has the same join combination as 1).
No. 1) has "song LEFT JOIN (song_artist JOIN artist)". 3) has "(song LEFT JOIN song_artist) JOIN artist". > Similarly trying a view using outer join > > CREATE VIEW songartistleftview AS SELECT song_artist.idSong AS idSong, > song_artist.idArtist AS idArtist, > artist.strArtist AS strArtist > FROM song_artist LEFT JOIN artist ON song_artist.idArtist = artist.idArtist > > New query > 4) SELECT song.*, songartistleftview.* FROM song > LEFT JOIN songartistleftview ON song.idSong = songartistleftview.idSong > WHERE song.idSong =1 > > 4) has same slow query plan as 1) despite having all left joins like 2). There are still differences: 2) has "(song LEFT JOIN song_artist) LEFT JOIN artist". 4) has "song LEFT JOIN (song_artist LEFT JOIN artist)". Regards, Clemens
