解决方法：
[Table("bma_products")] public class Product {
//加上[Key]即可 [Key] public int pid{get; set;} public string psn{get; set;} }
Linq------错误：EntityType: EntitySet 'Products' is based on type 'Product' that has no keys defined.
原文：http://www.cnblogs.com/tianhengblogs/p/6322249.html