In this article I will explain with an example, how to delete data from database using Dapper library in ASP.Net using C# and VB.Net.
 
 

Installing Dapper package using Nuget

In order to install Dapper library using Nuget, please refer my article Install Dapper from Nuget in Visual Studio.
 
 

Database

I have made use of the following table Customers with the schema as follows.
Delete using Dapper in ASP.Net
 
I have already inserted few records in the table.
Delete using Dapper in ASP.Net
 
Note: You can download the database table SQL by clicking the download link below.
          Download SQL file
 
 

HTML Markup

The HTML Markup consists of:
TextBox – For capturing CustomerId of the Customer record to be deleted.
Button – For deleting the record.
The Button has been assigned with an OnClick event handler.
<table border="0" cellpadding="0" cellspacing="0">
    <tr>
        <td style="width: 60px">Id<br />
            <asp:TextBox ID="txtId" runat="server" Width="50px" />
        </td>
        <td style="width: 200px"><br />
            <asp:Button Text="Delete" runat="server" OnClick="OnDelete" />
        </td>
    </tr>
</table>
 
 

Namespaces

You will need to import the following namespaces.
C#
using Dapper;
using System.Data.SqlClient;
using System.Configuration;
 
VB.Net
Imports Dapper
Imports System.Data.SqlClient
Imports System.Configuration
 
 

Deleting using Dapper in ASP.Net

When Delete button is clicked, first the connection is read from Web.Config file.
Note: For more details on how to read connection string from Web.Config file, please refer my article Read or Write Connection Strings in Web.Config file using ASP.Net using C# and VB.Net.
 
Then, using Execute method of Dapper library record is deleted from the SQL Server database.
Note: For more details on Execute method, please refer my article Understanding Dapper Execute in C# and VB.Net.
 
Finally, based on whether record is deleted or not, an appropriate message is displayed in JavaScript Alert Message Box using RegisterStartupScript method.
C#
protected void OnDelete(object sender, EventArgs e)
{
    string sql = "DELETE FROM Customers WHERE CustomerId = @CustomerId";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        int customerId = int.Parse(txtId.Text);
        int i = con.Execute(sql, new { customerId });
        if (i > 0)
        {
            ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('Customer record deleted.');", true);
        }
        else
        {
            ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('Customer not found.');", true);
        }
    }
}
 
VB.Net
Protected Sub OnDelete(ByVal sender As Object, ByVal e As EventArgs)
    Dim sql As String = "DELETE FROM Customers WHERE CustomerId = @CustomerId"
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Dim customerId As Integer = Integer.Parse(txtId.Text)
        Dim i As Integer = con.Execute(sql, New With {customerId})
        If i > 0 Then
            ClientScript.RegisterStartupScript(Me.GetType(), "alert", "alert('Customer record deleted.');", True)
        Else
            ClientScript.RegisterStartupScript(Me.GetType(), "alert", "alert('Customer not found.');", True)
        End If
    End Using
End Sub
 
 

Screenshot

Delete using Dapper in ASP.Net
 
 

Downloads

Download Code