protected void Page_Load(object sender, EventArgs e)
    {
        Response.ContentEncoding = Encoding.UTF8;
            db = new MyConnection(Server.MapPath(@"App_Data\"));
    }
protected void Button1_Click(object sender, EventArgs e)
    {
        string subject = "<b>" + TextBox1.Text + "</b>";
        
        string details = TextBox2.Text.Replace(Environment.NewLine, " <br /> ");
        try
        {
            db.Add_Recommendation(subject, details);
        }
        catch
        {
            //....
        }
    }

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
using Microsoft.SqlServer;
public class MyConnection
{
    SqlConnection connection;
    SqlDataAdapter adapter;
    SqlCommand command;
    private string GetConnectionString(string path)
    {
        return @"Data Source=.\SQLEXPRESS;AttachDbFilename=" + path + @"Database.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
    }
	public MyConnection(string dbpath)
	{
        connection = new SqlConnection(GetConnectionString(dbpath));
        command = new SqlCommand();
        command.Connection = connection;
        adapter = new SqlDataAdapter(command);
	}
    public DataTable GetDataTable(string cmd)
    {
        DataSet ds = new DataSet();
        command.CommandText = cmd;
        adapter.Fill(ds);
        return ds.Tables[0];
    }
    public void Add_Recommendation(string subject,string details)
    {
        int id = GetNewRecommandationId();
        command.CommandText = "INSERT INTO Recommendations (rec_id,subject_name,details) VALUES(@id_param,@subject_param,@details_param)";
        command.Parameters.Add("@id_param", SqlDbType.Decimal).Value = id;
        command.Parameters.Add("@subject_param", SqlDbType.VarChar).Value = subject;
        command.Parameters.Add("@details_param", SqlDbType.VarChar).Value = details;
        try
        {
            connection.Open();
            command.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            connection.Close();
        }
    }
    private int GetNewRecommandationId()
    {
        DataSet ds = new DataSet();
        command.CommandText = "SELECT TOP 1 rec_id FROM Recommendations ORDER BY rec_id DESC";
        adapter.Fill(ds);
        int id;
        if (ds.Tables[0].Rows.Count > 0)
            id = int.Parse(ds.Tables[0].Rows[0][0].ToString());
        else
            id = 0;
        return ++id;
    }
   //....