在下面的示例中:
my $rs = $schema->resultset('CD')->search( { 'artist.name' => 'Bob Marley' 'liner_notes.notes' => { 'like','%some text%' },},{ join => [qw/ artist liner_notes /],order_by => [qw/ artist.name /],} );
# Equivalent sql: # SELECT cd.*,artist.*,liner_notes.* FROM cd # JOIN artist ON cd.artist = artist.id # JOIN liner_notes ON cd.id = liner_notes.cd # WHERE artist.name = 'Bob Marley' # ORDER BY artist.name
但是从菜谱的其余部分开始,我一直认为查询只会选择cd.*,除非当然使用prefetch是这样的:
my $rs = $schema->resultset('CD')->search( { 'artist.name' => 'Bob Marley' 'liner_notes.notes' => { 'like',prefetch => [qw/ artist liner_notes/],} );
以下是让我相信这一点的陈述:
[Prefetch] allows you to fetch results from related tables in advance
任何人都可以向我解释我在这里缺少的东西吗?或不?非常感谢!