LINQ to SQL Group Join

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  Keywords : Linq to sql group join in c# / vb.net example, How to use linq to sql group join with multiple tables in c# / vb.net with example, Linq to sql group Join query with multiple conditions

Here we will learn LINQ to SQL Group join in c#, vb.net with example and how to use LINQ to SQL Group join to get sequence of elements from both the collections in c#, vb.net with example.

LINQ to SQL Group Join

In LINQ to SQL a Join clause with an into expression is called as a Group join. In LINQ to SQL the Group join produces a sequence of object elements based on the matching elements from both the collections.

Syntax of LINQ to SQL Group Join

Following is the syntax of using LINQ to SQL Group Join to get data from multiple tables.

 

var result = from ed in db.EmployeeDetails

join d in db.Departments on ed.DeptId equals d.DeptId into edept

from dpem in edept

select new

{

Name = ed.EmpName,

Department = dpem.DeptName

};

If you observe above syntax we joined “EmployeeDetails”, “Departments” tables to get required data by using group join.

Example of LINQ to SQL Group Join

Before we start implement LINQ to SQL group join example first we need to create a database with required tables and map those tables to LINQ to SQL file (.dbml) if you don't know the process don't worry check this link create and map database tables to LINQ to SQL file (.dbml).

 

Once we create and map required tables to .dbml file now we will show data in our application for that Right click on application → select Add → New Item → Select Web Form → Give name as Default.aspx and click OK button.

 

Now open Default.aspx page and write the code like as shown below

 

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

<title>Show Employee Details in Gridview</title>

</head>

<body>

<form id="form1" runat="server">

<div>

<asp:GridView ID="gvDetails" runat="server"></asp:GridView>

</div>

</form>

</body>

</html>

Now open code behind file and write the code like as shown below

 

protected void Page_Load(object sender, EventArgs e)

{

EmployeeDBDataContext db = new EmployeeDBDataContext();

if (!Page.IsPostBack)

{

var result = from ed in db.EmployeeDetails

join d in db.Departments on ed.DeptId equals d.DeptId into edept

from dpem in edept

select new

{

Name = ed.EmpName,

Location = ed.Location,

Gender = ed.Gender,

Department = dpem.DeptName

};

gvDetails.DataSource = result;

gvDetails.DataBind();

}

}

If you observe above example, we are trying to get data from “EmployeeDetails” and “Departments” table using Group join.

Output of LINQ to SQL Group Join

Following is the result of LINQ to SQL group join example.

 

LINQ to SQL Group Join Queries with Examples

 

This is how we can use LINQ to SQL Group join in c# to get required data from multiple tables based on our requirements.

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