private void FillInDataGrid(string SQLstring)
{
    string cn = ConfigurationManager.ConnectionStrings["Scratchpad"].ConnectionString; //hier wordt de databasestring opgehaald
    DataSet ds = new DataSet();
    // dispose objects that implement IDisposable
    using(SqlConnection myConnection = new SqlConnection(cn))
    {
        SqlDataAdapter dataadapter = new SqlDataAdapter(SQLstring, myConnection);

        // set the CommandTimeout
        dataadapter.SelectCommand.CommandTimeout = 60;  // seconds

        myConnection.Open();
        dataadapter.Fill(ds, "Authors_table"); 
    }
    dataGridView1.DataSource = ds;
    dataGridView1.DataMember = "Authors_table";
}

1-EntityFramework 
context.Database.SetCommandTimeout(60); //seconds

2-SqlDataAdapter
 dataAdapter.SelectCommand.CommandTimeout = 60;  // seconds