多表联查
select g.number,p.name,p.nowCost,u.realname,u.phone from wb_barter_goods as g left join wb_barter_users as u on g.usersId = u.id left join wb_barter_product as p on p.id = g.productId
where u.id = 1
原文：http://www.cnblogs.com/linglingyang/p/4709059.html