在我的应用程序中,有发布者和类别。一个发布者可以属于多个类别。当我进行mysql事务时,对于它所属的每个类别,它将返回相同的发布者记录。以下是查询:
SELECT grdirect_publisher.name, grdirect_publisher.short_description, grdirect_publisher.thumb_image, grdirect_publisher.url, grdirect_category.name AS catname FROM grdirect_publisher JOIN grdirect_publisher_categories ON grdirect_publisher.id = grdirect_publisher_categories.publisher_id JOIN grdirect_category ON grdirect_publisher_categories.category_id = grdirect_category.id
返回:
name short_description thumb_image url catname ------------------------------------------------------------ Foo Lorem Ipsum... images/pic.png d.com Video Games Foo Lorem Ipsum... images/pic.png d.com Music Bar Blah Blah... images/tic.png e.com Music
实际上,Foo在结果中只应该出现一次。