LinqToSQL不更新数据库

// goal: update Address record identified by "id", with new data in "colVal" string cstr = ConnectionApi.GetSqlConnectionString("SwDb"); // get connection str using (DataContext db = new DataContext(cstr)) { Address addr = (from a in db.GetTable () where a.Id == id select a).Single(); addr.AddressLine1 = colValue.Trim(); db.SubmitChanges(); // this seems to have no effect!!! } 在调试器中，addr具有db表中的所有当前值，并且我可以在调用db.SubmitChanges（）之前验证AddressLine1是否已更改。执行SubmitChanges行时，SQL Profiler仅显示“重置连接”。任何人都知道为什么这不起作用？谢谢！