未将对象引用设置到对象的实例

public void GetGoodsInfo()
    {
        string strSql = "select * from Goodsinfo where Goodsid=" + Convert.ToInt32(Request["id"].Trim());
        SqlCommand myCmd = db0bj.GetCommandStr(strSql);
        DataTable dsTable = db0bj.GetDataSetStr(strSql, "Gdif");
        this.txtCategory.Text = gc0bj.GetClass(Convert.ToInt32(dsTable.Rows[0]["TypeID"].ToString()));
        this.txtName.Text = dsTable.Rows[0]["Goodsname"].ToString();
        this.txtAuthor.Text = dsTable.Rows[0]["Goodsauthor"].ToString();
        this.txtCompany.Text = dsTable.Rows[0]["Goodscompany"].ToString();
        this.txtMarketPrice.Text = dsTable.Rows[0]["Goodsmarketprice"].ToString();
        this.txtHotPrice.Text = dsTable.Rows[0]["GoodshotPrice"].ToString();
        this.ImageMapPhoto.ImageUrl = dsTable.Rows[0]["Goodsurl"].ToString();
        this.cbxCommend.Checked = dsTable.Rows[0]["Isrefinement"].ToString();


        this.isbool(cbxCommend, dsTable.Rows[0]["Isrefinement"].ToString());
        this.isbool(cbxDiscount, dsTable.Rows[0]["IsDiscount"].ToString());
        this.isbool(cbxHot, dsTable.Rows[0]["IsHot"].ToString());
        this.txtShortDesc.Text = dsTable.Rows[0]["GoodsIntroduce"].ToString();
    }
    protected void btnBack_Click(object sender, EventArgs e)
    {
        string strUrl = Session["address"].ToString();
        Response.Redirect(strUrl);
    }
    public void isbool(CheckBox c, string s)
    {
        if (s=="1")
        {
            c.Checked = true;
            return;
        }
else
{
   c.Checked = false;
    return;


我是新手，实在不明白错在哪里了，很是郁闷……希望高手能给我一点儿指教！谢谢……
还有我在数据库中将Isrefinement,Isdiscount,Ishot的数据类型设置为char类型了，在这里无法将string转换为bool类型。但是在sql server 数据库中没有bool类型，只有bit类型，怎么办？在数据库中修改它的类型会提示丢失数据，最后还是没有修改成功，怎么办？