public void LoadModelByCategoryAndBrand() { List <Model> models = sql.getModelByCategoryAndBrandAll(comboBox_Categories.Text, comboBox_Brands.Text); comboBox_Model.DataSource = models; comboBox_Model.DisplayMember = "nameModel"; comboBox_Model.ValueMember = "nameModel"; if (device != null) { comboBox_Model.Text = device.Model; } models = null; }