String de Conexão C# com SQL Server

namespace utilizado : System.Data.SqlClient

private void button1_Click(object sender, EventArgs e)

{
   try{
    
    DataTable dt = new DataTable();

    string strConn = @"Server = .\sqlexpress;Database = BancoDados; Integrated Security = SSPI;";

    SqlConnection conn = new SqlConnection(strConn);

    SqlDataAdapter da = new SqlDataAdapter("Select * from NomeTabela", conn);

    da.Fill(dt);
    //exibe os dados no DataGridView
    gdvDadosSQLServer.DataSource = dt.DefaultView;
    }
    catch (Exception ex)
    {
        MessageBox.Show("Erro : " + ex.Message);
    }
}