//读取当前对象的属性值
public void EFReadEnitityInfo()
{
var result = learndb.ustudent.Where(o => o.gid == "02").First();
result.ssexy = "无";
var originalValue = learndb.Entry(result).Property(c => c.ssexy).OriginalValue;
var currentValue = learndb.Entry(result).Property(c => c.ssexy).CurrentValue;
var databaseValue = learndb.Entry(result).GetDatabaseValues().GetValue <string>("ssexy");
Console.WriteLine("初始值为：{0}，当前值为：{1}，数据库中值为：{2}", originalValue, currentValue, databaseValue);
}
// @see search "EF模型增删改查"
private void button_delete_Click(object sender, EventArgs e)
{
//lqRecCustTransDataContext
sail_heEntities db = new sail_heEntities();
ustudent delete = new ustudent();
delete.sid = int.Parse(studentS[listBox_main.SelectedIndex].getStuId());
db.Entry(delete).State = System.Data.Entity.EntityState.Deleted;
studentS.RemoveAt(listBox_main.SelectedIndex);
Clear();
studentS.ForEach(ele => WriteLine(ele.tabString()));
db.SaveChanges();
/*
* var q = (from c in db.ustudent
* where c.sid == tb_UserInf.CreateUser && c.AutoId == iAid
* select c).First();
* db.ustudent.DeleteOnSubmit(q);
* db.ustudent.delete
*
* var q2 = db.ustudent.First(c => c.AutoId == iAid && c.CreateUser == tb_UserInf.CreateUser);
* db.ustudent.DeleteOnSubmit(q2);
*
* @see https://docs.microsoft.com/zh-cn/dotnet/framework/data/adonet/sql/linq/how-to-delete-rows-from-the-database
* // Query the database for the rows to be deleted.
* var deleteOrderDetails =
* from details in db.ustudent
* where details.sid == 11000
* select details;
*
* foreach (var detail in deleteOrderDetails)
* {
* db.ustudent.DeleteOnSubmit(detail);
* }
*
* try
* {
* db.SubmitChanges();
* }
* catch (Exception e)
* {
* Console.WriteLine(e);
* // Provide for exceptions.
* }*/
}