asp.net 多条件查询

  string sql = "select * from  [product] where 1=1";
        //商品名称不为空
        if (shopName != "")
        {
            sql += " and [proName]='" + shopName + "'";
        }
        //商品编号不为空
        if (Number != "")
        {
            sql += " and [proOwnerId]='" + Number + "'";
        }
        //商品说明不为空
        if (shopRemark != "")
        {
            sql += " and [promiaoshu]=" + shopRemark + "'";
        }
        //一级类别不为空
        if (dropClass != "")
        {
            sql += " and [proclass]='" + dropClass + "'";
        }
        //二级类别不为空
        if (dropclass1 != "")
        {
            sql += " and [class]='" + dropclass1 + "'";
        }
        //三级类别不为空
        if (dropclass2 != "")
        {
            sql += " or [ThreeClass]='" + dropclass2 + "'";
        }