Insert Data to Database in ASP.Net Three Tier Architecture using C#

Hi leandro.tende...,

Please refer below sample.

Database

I have made use of the following table Customers with the schema as follows. 

I have already inserted few records in the table.

You can download the database table SQL by clicking the download link below.

Download SQL file

HTML

<table>
    <tr>
        <td>Name:</td>
        <td><asp:TextBox ID="txtName" runat="server" /></td>
    </tr>
    <tr>
        <td>Country:</td>
        <td><asp:TextBox ID="txtCountry" runat="server" /></td>
    </tr>
</table>
<asp:Button Text="Submit" OnClick="Submit" runat="server" />

Namespaces

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

Code 

protected void Submit(object sender, EventArgs e)
{
    string lastId = BLL.BusinessModel.InsertCustomer(txtName.Text, txtCountry.Text);
    ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('" + lastId + "');", true);
}

Class

DAL

public static class DataAccessModel
{
    public static string conn()
    {
        return @"Server=.\SQL2019;DataBase=Test;UID=sa;PWD=pass@123";
    }

    public static string ExecutaSQLScalarString(string sql)
    {
        using (SqlConnection con = new SqlConnection(conn()))
        {
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                con.Open();
                string res = Convert.ToString(cmd.ExecuteScalar());
                con.Close();

                return res;
            }
        }
    }
}

BLL

public static class BusinessModel
{
    public static string InsertCustomer(string name, string country)
    {
        string query = string.Format("INSERT INTO Customers VALUES ('{0}','{1}');SELECT SCOPE_IDENTITY();", name, country);
        return DAL.DataAccessModel.ExecutaSQLScalarString(query);
    }
}

Screenshot

Output