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2019-09-17 17:50:49 【大中小】浏览:48次

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o) //{ // Response.Write(orderinfo.OrderNumber); //} //也可这样写，直接查询orderinfo表 var orderinfolist = from o in db.OrderInfo where o.CustomerId1 == 1 select o; foreach (var orderinfo in orderinfolist) { Response.Write(orderinfo.OrderNumber); } }

7、通过Customer的num查找orderinfo的name：

 protected void Button4_Click(object sender, EventArgs e)
        {
            Model3Container db = new Model3Container();
            var orderinfolist = from c in db.OrderInfo
                            where c.OrderNumber =="1001"
                            select c;
            var orderinfo = orderinfolist.FirstOrDefault();
            Customer customer = orderinfo.Customer;
            Response.Write(customer.CustomerName);
        }

8、删除表orderlist中，customerid=1

        protected void Button5_Click(object sender, EventArgs e)
        {
            Model3Container db = new Model3Container();
            var customer = (from c in db.Customer
                            where c.Id == 1
                            select c
                          ).FirstOrDefault();
            var orderinfolist = customer.OrderInfo;
            while (orderinfolist.Count > 0)
            {
                var orderinfo = orderinfolist.FirstOrDefault();
                db.Entry<OrderInfo>(orderinfo).State = System.Data.EntityState.Deleted;
            }
            db.SaveChanges();
        }

9、查询部分列：

 1         protected void Button6_Click(object sender, EventArgs e)
 2         {
 3             book_shop3Entities db = new book_shop3Entities();
 4             var userinfolist = from u in db.UserInfo
 5                                where u.ID == 92
 6                                select new { Uname = u.UserName, Upwd = u.UserPass };
 7             foreach (var userinfo in userinfolist)
 8             {
 9                 Response.Write(userinfo.Uname + ":" + userinfo.Upwd);
10             }
11         }

10、lamada表达式进行查询：

 protected void Button7_Click(object sender, EventArgs e)
        {
            book_shop3Entities db = new book_shop3Entities();
            var userinfolist = db.UserInfo.Where<UserInfo>(u => u.ID == 92);
            foreach (var userinfo in userinfolist)
            {
                Response.Write(userinfo.UserName);
            }
        }

11、进行分页排序的例子：

 1         protected void Button8_Click(object sender, EventArgs e)
 2         {
 3             book_shop3Entities db = new book_shop3Entities();
 4             //var userinfolist = db.UserInfo.Where<UserInfo>(u => u.ID == 92);
 5             //升序排序
 6             // var userinfolist = db.UserInfo.Where<UserInfo>(u => true).OrderBy<UserInfo, int>(u => u.ID);
 7             //降序排序
 8             //  var userinfolist = db.UserInfo.Where<UserInfo>(u => true).OrderByDescending(u => u.ID);
 9             //分页
10             int pageindex = 2;
11             int pagesize = 2;
12             //var userinfolist = (from u in db.UserInfo
13             //                    where u.ID > 0
14             //                    orderby u.ID descending
15             //                    select u).Skip<UserInfo>((pageindex - 1) * pagesize).Take<UserInfo>(pagesize);
16             //skip：表示跳过多少条记录，take取多少条记录
17             var userinfolist = db.UserInfo.Where<UserInfo>(u => true).OrderByDescending(u => u.ID).Skip<UserInfo>((pageindex - 1) * pagesize).Take<UserInfo>(pagesize);
18 
19 
20             foreach (var userinfo in userinfolist)
21             {
22                 Response.Write(userinfo.UserName);
23             }
24         }

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