Asp.net Linq implements group query

First, create a person. cs class.
Public class person
{
Public string name
{Get; set ;}
Public int age
{Get; set ;}
Public string sex
{Get; set ;}
}
Next we will add data to this person class:
List <person> plist1 = new List <person> ();
 
Plist1.Add (new person {name = "cxx1", age = 24, sex = "male "});
Plist1.Add (new person {name = "www.baidu.com", age = 25, sex = "male "});
Plist1.Add (new person {name = "www.52mvc.com", age = 26, sex = "male "});
 
 
List <person> plist2 = new List <person> ();
 
 
Plist2.Add (new person {name = "cxx1", age = 24, sex = "male "});
Plist2.Add (new person {name = "cxx2", age = 28, sex = "male "});
Plist2.Add (new person {name = "cxx4", age = 27, sex = "male "});
Plist2.Add (new person {name = "cxx5", age = 28, sex = "male "});
// Asp.net
Var query = from person p in plist1
Join person per in plist2
On p. name equals per. name
Select new
{
Name = p. name,
Gender = p. sex,
Age = p. age
 
};
Gd2.DataSource = query;
Gd2.DataBind ();
 
The returned result is:
 
 

 
Note: This method is used to find data with the same name record in plist1 and plist2.
 
 
Next, let's take a look at how left join in SQL is implemented in linq.
Create two cs classes first.
 
/// <Summary>
/// Mobile phone list
/// </Summary>
Public class MobileStore
{
Public string mobId
{Set; get ;}
Public string mobName
{Set; get ;}
}
/// <Summary>
/// Mobile phone sales table
/// </Summary>
Public class MobileSale
{
Public string Sid
{Set; get ;}
Public string mobId
{Set; get ;}
Public string mobName
{Set; get ;}
Public string price
{Set; get ;}
}
 
 
List <MobileStore> listStore = new List <MobileStore> ();

ListStore. Add (new MobileStore {mobId = "1", mobName = "N86 "});
ListStore. Add (new MobileStore {mobId = "2", mobName = "N82 "});
ListStore. Add (new MobileStore {mobId = "3", mobName = "N81 "});
ListStore. Add (new MobileStore {mobId = "4", mobName = "N95 "});
ListStore. Add (new MobileStore {mobId = "5", mobName = "N85 "});
ListStore. Add (new MobileStore {mobId = "6", mobName = "N97 "});
 
List <MobileSale> listSale = new List <MobileSale> ();
ListSale. Add (new MobileSale {Sid = "1", mobId = "1", mobName = "N86", price = "100 "});
ListSale. Add (new MobileSale {Sid = "2", mobId = "2", mobName = "N82", price = "220 "});
ListSale. Add (new MobileSale {Sid = "3", mobId = "3", mobName = "N81", price = "300 "});
 
Var query = from MobileStore m in listStore
 
Join MobileSale sale in listSale
On m. mobId equals sale. mobId into joinm
 
From j in joinm. DefaultIfEmpty ()
Select new
{
ID = m. mobId,
Name = m. mobName,
Price = j = null? "No data": j. price,
};
Gd. DataSource = query;
Gd. DataBind ();