增加

using(var db = new Entities())

{

    //数据操作

    UserInfo user = new UserInfo()

    {

        UserName = "zhangsan1",

        UserPass = ""

    };

    db.UserInfo.Add(user);

    db.SaveChanges();

}

删除 先查询-再删除

using (var db = new Entities())

{

    var user = (from v in db.UserInfo

                where v.UserID ==

                select v).Single();

    db.UserInfo.Remove(user);

    db.SaveChanges();

}

修改单个实体 先查询-再修改

using (var db = new Entities())

{

    var user = (from v in db.UserInfo

                where v.UserName == "zhangsan"

                select v).Single();

    user.UserPass = "";

    db.SaveChanges();

}