Linq学习比较第2篇

参考程序:

//增
            t_User user = new t_User();
            user.UserName = "大气象";
            user.Pwd = "123456";
            ctx.t_User.InsertOnSubmit(user);//以前的方法是Add();
            ctx.SubmitChanges();

//改
            //参考这样的语法string s = (from a in ctx.Customers select a).Single(a => a.ID == 2);
            t_User userUpdate = ctx.t_User.SingleOrDefault(t_User => t_User.ID == 2);//Single与SingleOrDefault没区别
            userUpdate.UserName = "大气象1";
            ctx.SubmitChanges();

//删
            t_User userDelete = (from userinfo in ctx.t_User where userinfo.ID == 1 select userinfo).FirstOrDefault();
            if (userDelete != null)
            {
                ctx.t_User.DeleteOnSubmit(userDelete);
                ctx.SubmitChanges();
            }
     自己的程序：

//插入
            NorthwindDataContext dc = new NorthwindDataContext(@"Data Source=.\SQLEXPRESS;AttachDbFilename='c:\documents and settings\administrator\my documents\visual studio 2010\Projects\test\test\test.mdf';Integrated Security=True;User Instance=True");
            studentInfo stuInfo = new studentInfo();
            stuInfo.StudentName = "陈小春";
            stuInfo.studentAge = 35;
            dc.studentInfo.InsertOnSubmit(stuInfo);
            dc.SubmitChanges();
            //修改
            studentInfo updateInfo = dc.studentInfo.SingleOrDefault(studentInfo => studentInfo.studentid == 2);
            updateInfo.StudentName = "刘德华";
            dc.SubmitChanges();
            //删除
            studentInfo deleteInfo = (from userinfo in dc.studentInfo where userinfo.studentid == 1 select userinfo).SingleOrDefault();
            if(deleteInfo!=null)
            {
                dc.studentInfo.DeleteOnSubmit(deleteInfo);
                dc.SubmitChanges();
            }