LINQ to ADO.NET means using LINQ queries on objects in ADO.NET. The LINQ to ADO.NET will give us a chance to write LINQ queries on the enumerable objects in ADO.NET, and the LINQ to ADO.NET has three types of LINQ technologies available LINQ to Dataset, LINQ to SQL, and LINQ to Entities.
Syntax of LINQ to ADO.NET
Following is the syntax of writing LINQ queries on ADO.NET objects.
C# Code
var result = from dt in ds.Tables[0].AsEnumerable()
where (dt.Field<string>("Gender") == "Male")
select new
{
Name = dt.Field<string>("EmpName"),
Location = dt.Field<string>("Location"),
Gender = dt.Field<string>("Gender"),
};
VB.NET Code
Dim result = From dt In ds.Tables(0).AsEnumerable() Where (dt.Field(Of String)("Gender") = "Male") Select New With {.Name = dt.Field(Of String)("EmpName"), .Location = dt.Field(Of String)("Location"), .Gender = dt.Field(Of String)("Gender")}
If you observe the above syntax, we wrote LINQ queries on the ADO.NET dataset object “ds” to get the required data.
LINQ to ADO.NET Example
Here we will see how to use LINQ to ADO.NET with an example. For that, we will create one new web application, connect with SQL Server, and write queries on the ADO.NET object (dataset) using LINQ to display data in gridview.
First, we will create one new “EmployeeDetails” table in the database for that execute the following query in your database and insert some dummy data to show it in the application.
CREATE TABLE [dbo].[EmployeeDetails](
[EmpId] INT IDENTITY (1, 1) NOT NULL,
[EmpName] VARCHAR (50) NULL,
[Location] VARCHAR (50) NULL,
[Gender] VARCHAR (20) NULL
PRIMARY KEY CLUSTERED ([EmpId] ASC)
);
insert into EmployeeDetails values ('Suresh Dasari','Chennai','Male')
insert into EmployeeDetails values ('Rohini Alavala','Chennai','Female')
insert into EmployeeDetails values ('Praveen Alavala','Guntur','Male')
insert into EmployeeDetails values ('Sateesh Chandra','Vizag','Male')
insert into EmployeeDetails values ('Sushmitha','Vizag','Female')
Now we will create a new web application for that Go to File --> Select New --> Select Project like as shown below
Once we select a new project new popup will open in that select Asp.Net Empty Web Application and give name as “LINQtoADONET” and click OK to create the new web application.
Now we will add the web page to the application for that Right-click on your application à Select Add à New Item à Select Web Form à give name as “Default.aspx” and click OK button it will create a new page in the application.
Now open the Default.aspx page and write the code as shown below.
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1">
<title>Bind Gridview with LINQ to ADO.NET Operations</title>
<style type="text/css">
.GridviewDiv {font-size: 100%; font-family: 'Lucida Grande', 'Lucida Sans Unicode', Verdana, Arial, Helevetica, sans-serif; color: #303933;}
.headerstyle
{
color:#FFFFFF;border-right-color:#abb079;border-bottom-color:#abb079;background-color: #df5015;padding:0.5em 0.5em 0.5em 0.5em;text-align:center;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div class="GridviewDiv">
<asp:GridView ID="gvDetails" CssClass="Gridview" runat="server" AutoGenerateColumns="False">
<HeaderStyle CssClass="headerstyle" />
<Columns>
<asp:BoundField HeaderText="Name" DataField="Name" />
<asp:BoundField HeaderText="Location" DataField="Location" />
<asp:BoundField HeaderText="Gender" DataField="Gender" />
</Columns>
</asp:GridView>
</div>
</form>
</body>
</html>
Now open the code behind the file and write the code as shown below.
C# Code
using System;
using System.Web.UI;
using System.Data.SqlClient;
using System.Data;
namespace WebApplication2
{
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
BindGridview();
}
}
protected void BindGridview()
{
DataSet ds = new DataSet();
using (SqlConnection con = new SqlConnection("Data Source=SURESH\\SQLEXPRESS;Integrated Security=true;Initial Catalog=MySampleDB"))
{
con.Open();
SqlCommand cmd = new SqlCommand("select * from employeedetails", con);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(ds);
con.Close();
if (ds.Tables[0].Rows.Count > 0)
{
var result = from dt in ds.Tables[0].AsEnumerable()
where (dt.Field<string>("Gender") == "Male")
select new
{
Name = dt.Field<string>("EmpName"),
Location = dt.Field<string>("Location"),
Gender = dt.Field<string>("Gender"),
};
gvDetails.DataSource = result;
gvDetails.DataBind();
}
}
}
}
}
VB.NET Code
Imports System.Web.UI
Imports System.Data.SqlClient
Imports System.Data
Partial Class VBCode
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
If Not Page.IsPostBack Then
BindGridview()
End If
End Sub
Protected Sub BindGridview()
Dim ds As New DataSet()
Using con As New SqlConnection("Data Source=SURESH\SQLEXPRESS;Integrated Security=true;Initial Catalog=MySampleDB")
con.Open()
Dim cmd As New SqlCommand("select * from employeedetails", con)
cmd.CommandType = CommandType.Text
Dim da As New SqlDataAdapter(cmd)
da.Fill(ds)
con.Close()
If ds.Tables(0).Rows.Count > 0 Then
Dim result = From dt In ds.Tables(0).AsEnumerable() Where (dt.Field(Of String)("Gender") = "Male") Select New With {.Name = dt.Field(Of String)("EmpName"), .Location = dt.Field(Of String)("Location"), .Gender = dt.Field(Of String)("Gender")}
gvDetails.DataSource = result
gvDetails.DataBind()
End If
End Using
End Sub
End Class
If you observe the above example, we used the ADO.NET dataset object and written LINQ query on the dataset object to get details from the dataset where Gender is equal to “Male”. Now we will run the application and see the output.
Result of LINQ to ADO.NET Example
Following is the result of the LINQ to ADO.NET example.
This is how we can use the LINQ query on ADO.NET objects to get the required data based on our requirements.
