Linq 语法举例
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";
6.跳过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";
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)";
Linq 语法举例的更多相关文章
- Linq语法详细
闲言碎语 近期比较忙,但还是想写点什么,就分享一些基础的知识给大家看吧,希望能帮助一些linq新手,如果有其它疑问,可以进右上角群,进行交流探讨,谢谢. 开门见山 读这篇文章之前,我先说下,每一种搜索 ...
- Linq语法详细(转)
原文地址:http://www.cnblogs.com/knowledgesea/p/3897665.html 开门见山 读这篇文章之前,我先说下,每一种搜索结果集,我都以三种方式变现出来,为啦更好的 ...
- Linq To Sql中实现Left Join与Inner Join使用Linq语法与lambda表达式
当前有两个表,sgroup与sgroupuser,两者通过gKey关联,而sgroup表记录的是组,而sgroupuser记录是组中的用户,因此在sgroupuser中不一定有数据.需要使用Left ...
- Linq语法
希望能帮助一些linq新手. 开门见山 读这篇文章之前,我先说下,每一种搜索结果集,我都以三种方式变现出来,为啦更好的理解,希望不要嫌我啰嗦. 1.简单的linq语法 //1 var ss = fro ...
- Lamda和Linq语法对比详细
本人转载:http://www.cnblogs.com/knowledgesea/p/3897665.html 闲言碎语 近期比较忙,但还是想写点什么,就分享一些基础的知识给大家看吧,希望能帮助一些l ...
- LinQ 语法基础
LINQ (Language-Integrated Query,语言集成查询). LINQ to Objects.LINQ to SQL.LINQ to DataSet和LINQ to XML,它们分 ...
- Linq语法常见普通语法
闲言碎语 近期比较忙,但还是想写点什么,就分享一些基础的知识给大家看吧,希望能帮助一些linq新手,如果有其它疑问,可以进右上角群,进行交流探讨,谢谢. 开门见山 读这篇文章之前,我先说下,每一种搜索 ...
- C# LINQ语法详解
1.简单的linq语法 var ss = from r in db.Am_recProScheme select r; var ss1 = db.Am_recProScheme; string sss ...
- LINQ语法类似于SQL的语法
LINQ语法类似于SQL的语法如下, Models.BookStoreEntities 是从添加新建项中的数据--->ADO.NET实体数据模型--->从数据库生成--->使用5.0 ...
随机推荐
- 简单说明Python中的装饰器的用法
简单说明Python中的装饰器的用法 这篇文章主要简单说明了Python中的装饰器的用法,装饰器在Python的进阶学习中非常重要,示例代码基于Python2.x,需要的朋友可以参考下 装饰器对与 ...
- Facade 门面模式 外观模式
简介 作用: (1)封装一组交互类,一致地对外提供接口 (2)封装子系统,简化子系统调用 JDK中体现:java.util.logging包 java.lang.Class javax.faces.w ...
- Android 自定义日历
好久没来写博客了,这半年多发生了好多的事情,废话不多说,今天在公司里比较闲在,写一篇最近写的公司用到的控件——日历控件. 控件的功能比较少,根据需求只有选择开始时间和结束时间并返回时间段. 效果图如下 ...
- propertychange input change
IE678 支持propertychange事件,可以监听所有属性(包括自定义属性)的改变事件,包括手动修改输入框文本以及js修改输入框文本. propertychange事件有个特点就是不支持冒泡, ...
- sencha app build 到 Capturing theme image不执行
解决sencha app build 到 Capturing theme image不执行 今天电脑重装系统,重新安装了sencha cmd,但是在打包时,到了 Capturing theme ima ...
- Java中异常的基本应用(一)
在Java中,我们把异常当做一种对象来处理,正是异常机制的引入,使得我们的程序更加健壮.异常指示了一个不正常的条件,或者一个错误条件,简单地说就是一个中断了正常的指令流的事件.程序控制将无条件的抛至一 ...
- underscorejs-indexBy学习
2.19 indexBy 2.19.1 语法 _.indexBy(list, iteratee, [context]) 2.19.2 说明 给定一个list,和 一个用来返回一个在列表中的每个元素键 ...
- oracle删除互相关联的记录
今天遇到一个问题,在数据库中删除一条记录,但是在删除的时候报错了,报出该记录已经被其他子记录引用,想了好久不知道怎么做,后来发现报错提示信息中会提示删除该记录时影响了那个约束条件,于是思路出来了: 1 ...
- JS冒泡事件与处理
JavaSciprt事件中有两个很重要的特性:事件冒泡以及目标元素. 事件冒泡: 当一个元素上的事件被触发的时候,比如说鼠标点击了一个按钮,同样的事件将会在那个元素的所有祖先元素中被触发.这 一过程被 ...
- Codeforces 301_div.2_Ice Cave(BFS走冰块)
Ice Cave Time Limit:2000MS Memory Limit:262144KB 64bit IO Format:%I64d & %I64u Descripti ...