实体框架左联接

改编自MSDN，如何使用EF 4退出联接

var query = from u in usergroups join p in UsergroupPrices on u.UsergroupID equals p.UsergroupID into gj from x in gj.DefaultIfEmpty() select new {      UsergroupID = u.UsergroupID,     UsergroupName = u.UsergroupName,     Price = (x == null ? String.Empty : x.Price)  };