MVC+EF

一、MVC+EF

不管是MVC 还是EF 都有文件夹 Controllers 下边的文件必须以Controller 结尾

WEBAPI 接口不要使用中文名称

二、Linq 查询

• 多表联查

• Linq 查询

• 1.简单的linq语法

   

   //1
              var ss = from r in db.Am_recProScheme
                       select r;
              //2
              var ss1 = db.Am_recProScheme;
              //3
              string sssql = "select * from Am_recProScheme";

   

   

  2.带where的查询

   

   //1
              var ss = from r in db.Am_recProScheme
                       where r.rpId > 10
                       select r;
              //2
              var ss1 = db.Am_recProScheme.Where(p => p.rpId > 10);
              //3
              string sssql = "select * from Am_recProScheme where rpid>10";

   

   

  3.简单的函数计算（count，min，max，sum）

   

              //1
              ////获取最大的rpId
              //var ss = (from r in db.Am_recProScheme
              //          select r).Max(p => p.rpId);
              ////获取最小的rpId
              //var ss = (from r in db.Am_recProScheme
              //          select r).Min(p => p.rpId);
              //获取结果集的总数
              //var ss = (from r in db.Am_recProScheme                  
              //         select r).Count();
              //获取rpId的和
              var ss = (from r in db.Am_recProScheme
                        select r).Sum(p => p.rpId);
  ?
  ?
              //2
              //var ss1 = db.Am_recProScheme.Max(p=>p.rpId);
              //var ss1 = db.Am_recProScheme.Min(p => p.rpId);
              //var ss1 = db.Am_recProScheme.Count() ;
              var ss1 = db.Am_recProScheme.Sum(p => p.rpId);
              Response.Write(ss);
  ?
              //3
              string sssql = "select max(rpId) from Am_recProScheme";
                     sssql = "select min(rpId) from Am_recProScheme";
                     sssql = "select count(1) from Am_recProScheme";
                     sssql = "select sum(rpId) from Am_recProScheme";

   

   

  4.排序order by desc/asc

   

              var ss = from r in db.Am_recProScheme
                       where r.rpId > 10
                       orderby r.rpId descending  //倒序
                       //  orderby r.rpId ascending   //正序
                       select r;
  ?
              //正序
              var ss1 = db.Am_recProScheme.OrderBy(p => p.rpId).Where(p => p.rpId > 10).ToList();
              //倒序
              var ss2 = db.Am_recProScheme.OrderByDescending(p => p.rpId).Where(p => p.rpId > 10).ToList();
  ?
              string sssql = "select * from Am_recProScheme where rpid>10 order by rpId [desc|asc]";

   

   

  5.top(1)

   

   //如果取最后一个可以按倒叙排列再取值
              var ss = (from r in db.Am_recProScheme                     
                        select r).FirstOrDefault();
  ?
              //（）linq to ef 好像不支持 Last() 
              var ss1 = db.Am_recProScheme.FirstOrDefault();
              //var ss1 = db.Am_recProScheme.First();          
  ?
              string sssql = "select top(1) * from Am_recProScheme";

   

  前面多少条数据取余下的数据

   

   //1
              var ss = (from r in db.Am_recProScheme
                        orderby r.rpId descending
                        select r).Skip(10); //跳过前10条数据，取10条之后的所有数据   
              //2  
              var ss1 = db.Am_recProScheme.OrderByDescending(p => p.rpId).Skip(10).ToList();
              //3
              string sssql = "select * from  (select ROW_NUMBER()over(order by rpId desc) as rowNum, * from [Am_recProScheme]) as t where rowNum>10";
   

   

  7.分页数据查询

   

    //1
              var ss = (from r in db.Am_recProScheme
                        where r.rpId > 10
                        orderby r.rpId descending
                        select r).Skip(10).Take(10); //取第11条到第20条数据                   
  ?
              //2 Take(10): 数据从开始获取，获取指定数量（10）的连续数据
              var ss1 = db.Am_recProScheme.OrderByDescending(p => p.rpId).Where(p => p.rpId > 10).Skip(10).Take(10).ToList();
              //3
              string sssql = "select * from  (select ROW_NUMBER()over(order by rpId desc) as rowNum, * from [Am_recProScheme]) as t where rowNum>10 and rowNum<=20";
   

   

  8.包含，类似like ‘%%‘

   

    //1
              var ss = from r in db.Am_recProScheme
                       where r.SortsText.Contains("张")
                       select r;
              //2
              var ss1 = db.Am_recProScheme.Where(p => p.SortsText.Contains("张")).ToList();
              //3
              string sssql = "select * from Am_recProScheme where SortsText like ‘%张%‘";
   

   

  9.分组group by

   

              //1
              var ss = from r in db.Am_recProScheme
                       orderby r.rpId descending
                       group r by r.recType into n
                       select new
                       {
                           n.Key,  //这个Key是recType
                           rpId = n.Sum(r => r.rpId), //组内rpId之和
                           MaxRpId = n.Max(r => r.rpId),//组内最大rpId
                           MinRpId = n.Min(r => r.rpId), //组内最小rpId
                       };
              foreach (var t in ss)
              {
                  Response.Write(t.Key + "--" + t.rpId + "--" + t.MaxRpId + "--" + t.MinRpId);
              }
              //2
              var ss1 = from r in db.Am_recProScheme
                       orderby r.rpId descending
                       group r by r.recType into n
                       select n;
              foreach (var t in ss1)
              {
                  Response.Write(t.Key + "--" + t.Min(p => p.rpId));
              }
              //3
              var ss2 = db.Am_recProScheme.GroupBy(p => p.recType);
              foreach (var t in ss2)
              {
                  Response.Write(t.Key + "--" + t.Min(p => p.rpId));
              }
              //4
              string sssql = "select recType,min(rpId),max(rpId),sum(rpId) from Am_recProScheme group by recType";           //多字段

   

  var result = (from item in data group item by new { item.Name, item.Type } into items select new { items.Key.Name, items.Key.Type, Cnt = items.Count() }).ToList();

var s = data.GroupBy(p => new { p.Type, p.Name }).Select(p=>new { p.Key.Type, p.Key.Name, cnt=p.Count() }).ToList();

10.连接查询

 //1
            var ss = from r in db.Am_recProScheme
                     join w in db.Am_Test_Result on r.rpId equals w.rsId
                     orderby r.rpId descending
                     select r;
            //2
            var ss1 = db.Am_recProScheme.Join(db.Am_Test_Result, p => p.rpId, r => r.rsId, (p, r) => p).OrderByDescending(p => p.rpId).ToList();
            //3
            string sssql = "select r.* from  [Am_recProScheme] as r inner join [dbo].[Am_Test_Result] as t on r.[rpId] = t.[rsId] order by r.[rpId] desc";
 

11.sql中的In

            //1
            var ss = from p in db.Am_recProScheme
                              where (new int?[] { 24, 25,26 }).Contains(p.rpId)
                              select p;
            foreach (var p in ss)
            {
                Response.Write(p.Sorts);
            }
            //2
            string st = "select * from Am_recProScheme where rpId in(24,25,26)";

• 匿名类型return Json(new {totalcount,totalpage,list });

三、Postman使用

四、MVC访问API

• WEBAPI 配置 跨域 （CORS）

跨域请求:将文件复制到API项目中的Web.config文件中 在下插入此段代码

跨域设置:将文件复制到API项目中的Global.asax文件中,在WebApiApplication方法中插入此段代码

原文：https://www.cnblogs.com/unique-tongxue/p/15042639.html