TP5 多个拥有相同字段的数据组合，某个字段相加

$res = \db('BooksInfo')->alias('bi')->join('user u','bi.user_id = u.uid')->field('info,state,yy_time,uid,sum(bi.books_price) as books_price')->group('yy_time,uid')->order('books_id desc')->paginate($_GET['limit']);

field：必须出现的字段，用‘，’隔开

group：需要合并的条件字段

sum(bi.books_price) as books_price：sum()集合 as books_price别名填写你要集合的字段