EF增删改查

 

//添加

UserInfo userInfo = new UserInfo();
userInfo.Email = "sss@256.com";
userInfo.RegTime = DateTime.Now;
userInfo.UserName = "sss56";
userInfo.UserPass="123456";

EFFristModelEntities db = new EFFristModelEntities();
db.UserInfo.Add(userInfo);//将数据添加到EF并且添加了添加标记。
db.SaveChanges();//数据才会保存到数据库。,返回受影响的行数。
Response.Write(userInfo.ID);

=================================================================

//删除

EFFristModelEntities db = new EFFristModelEntities();
//var userInfoList = from u in db.UserInfo
// where u.ID == 345
// select u;
//UserInfo userInfo=userInfoList.FirstOrDefault();//返回第一个元素，如果没有的话，返回null
//if (userInfo != null)
//{
// // db.UserInfo.Remove(userInfo);
// db.Entry<UserInfo>(userInfo).State = System.Data.EntityState.Deleted;

// db.SaveChanges();
//}
//else
//{
// Response.Write("要删除的数据不存在!!");
//}

UserInfo userInfo = new UserInfo() {ID=344};
//db.UserInfo.Remove(userInfo);
db.Entry<UserInfo>(userInfo).State = System.Data.EntityState.Deleted;
db.SaveChanges();

//查询

protected void Button2_Click(object sender, EventArgs e)
{
EFFristModelEntities db = new EFFristModelEntities();
//linq
var userInfoList = from u in db.UserInfo
where u.ID ==343
select u;
int i = 0;

foreach (UserInfo userInfo in userInfoList)//EF 延迟加载机制，数据用到的时候才去数据库中查询。不能用的时候不查询。
{
Response.Write(userInfo.UserName);
}

// select * from UserInfo where ID=343
// from UserInfo
// where ID=343
// select *
}

//更新

protected void Button4_Click(object sender, EventArgs e)
{
EFFristModelEntities db = new EFFristModelEntities();
var userInfoList = from u in db.UserInfo
where u.ID == 343
select u;
var userInfo = userInfoList.FirstOrDefault();
userInfo.UserPass = "666666";
db.Entry<UserInfo>(userInfo).State = System.Data.EntityState.Modified;
db.SaveChanges();
}