private void btnAdd_Click(object sender, EventArgs e) { Connector databaseConnect = new MYSQLDatabaseConnection(); DatabaseColumn databaseColumn = new DatabaseColumn(); databaseColumn.category_name = txtCategoryName.Text.ToString(); databaseColumn.category_id = txtCategoryId.Text.ToString(); databaseConnect.SetData(databaseColumn); if (databaseConnect.establish() == true && databaseConnect.InsertCategoryDetails() == true) { var list = new List <DatabaseColumn>() { new DatabaseColumn { category_name = txtCategoryName.Text.ToString(), category_id = txtCategoryId.Text.ToString() } }; CombineDataGridView combineDataGridView = new CombineDataGridView(); combineDataGridView.SetDataGridViewList(list, mDgv);//connect main window datagridview txtCategoryId.Clear(); txtCategoryName.Clear(); } else { MessageBox.Show("operation error"); } }