Linq to sql之left join运用示例
示例一:
var l= from a in cardsBll.GetCards()
join b in usersBll.GetAllUsers()
on a.CardSn equals b.CardSn into temp
where a.CardSn.Contains(key)
from t in temp.DefaultIfEmpty()
select new CardsAndUsersView
{
Card_Id = a.Id,
CardPw = a.CardPw,
Expries = a.Expries,
IsEnabled = a.IsEnabled,
CardSn = a.CardSn,
CreateDate = a.CreateDate,
ModifyDate = a.ModifyDate,
User_Id = t==null?0:t.Id,
Province = t == null ? "" : t.Province,
City = t == null ? "" :t.City,
AreaOrCounty = t == null ? "" : t.AreaOrCounty,
AddressInfo = t == null ? "" : t.AddressInfo
};
生成的SQL如下:
exec sp_executesql N'SELECT TOP (20)
[Project1].[Id] AS [Id],
[Project1].[CardPw] AS [CardPw],
[Project1].[Expries] AS [Expries],
[Project1].[IsEnabled] AS [IsEnabled],
[Project1].[CardSn] AS [CardSn],
[Project1].[CreateDate] AS [CreateDate],
[Project1].[ModifyDate] AS [ModifyDate],
[Project1].[C1] AS [C1],
[Project1].[C2] AS [C2],
[Project1].[C3] AS [C3],
[Project1].[C4] AS [C4],
[Project1].[C5] AS [C5]
FROM ( SELECT [Project1].[Id] AS [Id], [Project1].[CardSn] AS [CardSn], [Project1].[CardPw] AS [CardPw], [Project1].[IsEnabled] AS [IsEnabled], [Project1].[Expries] AS [Expries], [Project1].[CreateDate] AS [CreateDate], [Project1].[ModifyDate] AS [ModifyDate], [Project1].[C1] AS [C1], [Project1].[C2] AS [C2], [Project1].[C3] AS [C3], [Project1].[C4] AS [C4], [Project1].[C5] AS [C5], row_number() OVER (ORDER BY [Project1].[Id] ASC) AS [row_number]
FROM ( SELECT
[Extent1].[Id] AS [Id],
[Extent1].[CardSn] AS [CardSn],
[Extent1].[CardPw] AS [CardPw],
[Extent1].[IsEnabled] AS [IsEnabled],
[Extent1].[Expries] AS [Expries],
[Extent1].[CreateDate] AS [CreateDate],
[Extent1].[ModifyDate] AS [ModifyDate],
CASE WHEN ([Extent2].[Id] IS NULL) THEN 0 ELSE [Extent2].[Id] END AS [C1],
CASE WHEN ([Extent2].[Id] IS NULL) THEN N'''' ELSE [Extent2].[Province] END AS [C2],
CASE WHEN ([Extent2].[Id] IS NULL) THEN N'''' ELSE [Extent2].[City] END AS [C3],
CASE WHEN ([Extent2].[Id] IS NULL) THEN N'''' ELSE [Extent2].[AreaOrCounty] END AS [C4],
CASE WHEN ([Extent2].[Id] IS NULL) THEN N'''' ELSE [Extent2].[AddressInfo] END AS [C5]
FROM [dbo].[Cards] AS [Extent1]
LEFT OUTER JOIN [dbo].[UserInfo] AS [Extent2] ON ([Extent1].[CardSn] = [Extent2].[CardSn]) OR (([Extent1].[CardSn] IS NULL) AND ([Extent2].[CardSn] IS NULL))
WHERE (1 = [Extent1].[IsEnabled]) AND ([Extent1].[CardSn] LIKE @p__linq__0 ESCAPE N''~'')
) AS [Project1]
) AS [Project1]
WHERE [Project1].[row_number] > 0
ORDER BY [Project1].[Id] ASC',N'@p__linq__0 nvarchar(4000)',@p__linq__0=N'%%'
执行结果:
页面效果:
示例二:
DataClasses1DataContext db = new DataClasses1DataContext();
var leftJoinSql = from student in db.Student
join book in db.Book on student.ID equals book.StudentID into temp
from tt in temp.DefaultIfEmpty()
select new
{
sname= student.Name,
bname = tt==null?"":tt.Name
};
Linq to sql之left join运用示例的更多相关文章
- LINQ TO SQL 中的join(转帖)
http://www.cnblogs.com/ASPNET2008/archive/2008/12/21/1358152.html join对于喜欢写SQL的朋友来说还是比较实用,也比较容易接受的东西 ...
- LINQ to SQL语句之Join和Order By
Join操作 适用场景:在我们表关系中有一对一关系,一对多关系,多对多关系等.对各个表之间的关系,就用这些实现对多个表的操作. 说明:在Join操作中,分别为Join(Join查询), SelectM ...
- Linq To SQL LEFT OUTER JOIN (Left Join)
SQL: SELECT [t0].[ProductName], [t1].[TotalPrice] AS [TotalPrice] FROM [Product] AS [t0] LEFT OUTER ...
- LINQ体验(6)——LINQ to SQL语句之Join和Order By
Join操作 适用场景:在我们表关系中有一对一关系,一对多关系.多对多关系等.对各个表之间的关系,就用这些实现对多个表的操作. 说明:在Join操作中.分别为Join(Join查询), SelectM ...
- Linq to SQL 参考Demo
LINQ to SQL语句()之Where Where操作 适用场景:实现过滤,查询等功能. 说明:与SQL命令中的Where作用相似,都是起到范围限定也就是过滤作用的,而判断条件就是它后面所接的子句 ...
- Linq to SQL各种参考
原文:https://www.cnblogs.com/lyj/archive/2008/01/23/1049686.htmlhttps://www.cnblogs.com/lyj/archive/20 ...
- Linq to SQL 语法查询(链接查询,子查询 & in操作 & join,分组统计等)
Linq to SQL 语法查询(链接查询,子查询 & in操作 & join,分组统计等) 子查询 描述:查询订单数超过5的顾客信息 查询句法: var 子查询 = from c i ...
- LINQ to SQL Count/Sum/Min/Max/Avg Join
public class Linq { MXSICEDataContext Db = new MXSICEDataContext(); // LINQ to SQL // Count/Sum/Min/ ...
- Linq To Sql 语法 子查询 & In & Join
子查询 描述:查询订单数超过5的顾客信息 查询句法: var 子查询 =from cin ctx.Customers where ...
随机推荐
- OpenJudge计算概论-骑车与走路
/*============================================================ 骑车与走路 总时间限制: 1000ms 内存限制: 65536kB 描述 ...
- Hive中导入Oracle数据错误:Listener refused the connection with the following error: ORA-12505
问题: 今天往Hive中导入Oracle数据的时候碰到了如下错误:Listener refused the connection with the following error: ORA-12505 ...
- sql中union,union all没有兼顾到的内容
今日遇到一个问题,两张表联合取交集去重,但是需要把某一字段相同的也给去掉 union all : 联合,没有取交集 union :联合取交集(仅针对所有字段相同的去重) 解决方案:将联合的数据作为一个 ...
- 双缓冲技术局部更新原理之派生自SurfaceView
package com.loaderman.customviewdemo; import android.content.Context; import android.graphics.Canvas ...
- 一台java服务器可以跑多少个线程?
一台java服务器能跑多少个线程?这个问题来自一次线上报警如下图,超过了我们的配置阈值. 京东自研UMP监控分析 打出jstack文件,通过IBM Thread and Monitor Dump ...
- c语言 GPS nmealib学习笔记
.nmealib简介 nmealib是一个基于C语言的用于nmea协议的开源库.虽然nmea体积小巧,但是却具备了不少功能. 分析NMEA语句并把结果保存在合适的C语言结构体中. 除了解析NMEA语句 ...
- java导入excel很完美的取值的方法
java导入excel很完美的取值的方法 1.解决方法: /** * 获取单元格数据内容为字符串类型的数据 * @param cell Excel单元格 * @return St ...
- Qt编写自定义控件37-发光按钮(会呼吸的痛)
一.前言 这个控件是好早以前写的,已经授权过好几个人开源过此控件代码,比如红磨坊小胖,此控件并不是来源于真实需求,而仅仅是突发奇想,类似于星星的闪烁,越到边缘越来越淡,定时器动态改变边缘发光的亮度,产 ...
- laravel php门面模式
门面模式 理解3个概念: 1)Container的概念,laravel所有的服务都注册在container里面,至于如何注册,就是使用service provider 2)service pr ...
- Node.js使用child_process调用系统命令示例
首先我们在D盘根目录下新建一个test.bat文件,他的内容如下: echo %date%%time% >> D:/test.txt 他的目的很简单,每次调用这个bat文件,都会在D:/t ...