mnbn.net
当前位置:首页 >> linq list join >>

linq list join

from A in DFZFORMT055 join B in FM_CODE_LIST on A.MoneyType = B.ITEM_VALUE AND B.FORM_KIND = 'DFZ.FORM.T055' AND B.FIELD_NAME= 'MoneyType' join C in JOIN FM_CODE_LIST on A.PayMentType = C.ITEM_VALUE AND C.FORM_KIND = 'DFZ.FORM....

我们在做SQL查询的时候经常会用到Inner Join,Left Join,笛卡尔积等等,连接方式的概念方面我想也不用给予太多解释, 我们今天的重点是让大家熟悉LINQ是如何使用Join来实现常用的表连接的。 创建测试用类: class Customer { public int Customer...

public class Person{ public int Pid{set;get;} public string Name{set;get;}}public class Scores{ public int Pid{set;get;} public int Score{set;get;}//分数 }上面两个类, SQL中你应该也能非常简单的想象出这两个表的结构,Scores表Pid...

在读取Student表时inner join Class表取的对应的Class信息: //inner join var query = from s in db.Students join c in db.Classes on s.ClassID equals c.ClassID where c.ClassID == 1 select new { ClassID = s.ClassID, ClassName = c.Cla...

IQueryable result = from c in db.GetTable() join t in db.GetTable() on new { id = c.ID, id1 = c.ID } equals new { id = t.ClassID, id1 = id } select new ClassInformation { ID = c.ID, ClassID = t.ClassID, Name = c.Name, TeacherNa...

这个问题的答案就是你知道的那两种方法,只有这两种方法: 要么用select new {a,b}; 要么用select new {a.字段1,a.字段2,b.字段1,b.字段2}

string.Join(string.Empty, MyString.ToArray())

Linq to Sql:var a=from g in Groupsjoin u in Userson g.Id equals u.GroupIdinto Grpfrom grp in Grp.DefaultIfEmpty()select new { GroupName=g.GroupName, UserName=(grp==null)?"":grp.UserName};var b=from u in Usersjoin g in Groupson ...

方法1: on new{o.id,0.code} equals new {p.id,p.code} 方法2: var tmp=from m in table1 from n in table2 where m.id==n.id && m.code==n.code select new{...}; 方法3: 你把后面的条件放在where语句里面去.

可以用 into 语法,配合 DefaultIfEmpty() 方法加载右侧表中的空值。例子:var query =from r in db.Rolesjoin sr in(from ss in db.StaffInRoleswhere ss.StaffId == staffIdselect ss)on r.Id equals sr.RoleIdinto xfrom y in x.DefaultIfEmp...

网站首页 | 网站地图
All rights reserved Powered by www.mnbn.net
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com