请教sql的语句怎样写？

请教下：当我在表单字段：F_SaleBillNo上输入单据号码时，触发datachanged
var @SaleNo = this.Model.GetValue("F_SaleBillNo");//此字段输入值时，
var rows = Kingdee.BOS.ServiceHelper.DBServiceHelper.ExecuteDynamicObject(
this.Context,
"Select FID FROM T_SAL_ORDER where FBillNo=@SaleNo");//where想取到这个输入值作为条件如何实现，where FBillNo=@SaleNo这样写不对呢
if (rows.Count > 0)
{

var SaleBillNo = rows[0]["FId"];

this.Model.SetValue("FAP_Remark", Convert.ToString(SaleBillNo));

}