this.cboVendor.SelectedIndexChanged -= new System.EventHandler(this.cboVendor_SelectedIndexChanged);                     cboVendor.DataSource =  myClass.RunQueryCmd(strSqlCmd);            cboVendor.DisplayMember = "SupplierCode";             //添加事件         this.cboVendor.SelectedIndexChanged += new System.EventHandler(this.cboVendor_SelectedIndexChanged);