请高手帮我看看 我的购物车程序 的奇怪问题。
这是我的“加入购物车”系统,当多次加入同一个商品时，（数量和总价计算都正常），但如果加入了另一个商品时，就出问题了。DataTable   中总会多出不需要的行。
请大家帮我看看。急用！

protected   void   BtnAddToCar_Click(object   sender,   EventArgs   e)
{
int   goodsId   =   Int32.Parse(this.DetailsView1.Rows[0].Cells[1].Text);
string   theGoodsName   =   (this.DetailsView1.Rows[1].Cells[1].Text).ToString();
decimal   thePrice   =   Convert.ToDecimal(this.DetailsView1.Rows[5].Cells[1].Text);

//DataTable   dtb   =   Session[ "myCar "]   as   DataTable;

if   (Session[ "myCar "]   ==   null)
{
DataTable   dtb   =   new   DataTable();
dtb.Columns.Add( "goodsId ",   typeof(int));
dtb.Columns.Add( "thtGoodsName ");
dtb.Columns.Add( "thePrice ");
dtb.Columns.Add( "TheCount ");
dtb.Columns.Add( "TotalPrice ");


DataRow   dRow   =   dtb.NewRow();
dRow[ "goodsId "]   =   goodsId;
dRow[ "thtGoodsName "]   =   theGoodsName;
dRow[ "thePrice "]   =   thePrice;
dRow[ "TheCount "]   =   1;
dRow[ "TotalPrice "]   =   thePrice;
dtb.Rows.Add(dRow);
Session[ "myCar "]   =   dtb;

}

else
{
DataTable   dtb   =   Session[ "myCar "]   as   DataTable;
for   (int   i   =   0;   i   <   dtb.Rows.Count;   i++)
{
if   (Convert.ToInt32(dtb.Rows[i][0])   ==   goodsId)
{
DataRow   oldDR;
oldDR   =   dtb.Rows[i];
oldDR[ "TheCount "]   =   Int32.Parse(oldDR[ "TheCount "].ToString())   +   1;
oldDR[ "thePrice "]   =   thePrice;

oldDR[ "TotalPrice "]   =   thePrice   *   Int32.Parse(oldDR[ "TheCount "].ToString());
}
else
{
DataRow   dRow   =   dtb.NewRow();
dRow[ "goodsId "]   =   goodsId;
dRow[ "thtGoodsName "]   =   theGoodsName;
dRow[ "thePrice "]   =   thePrice;
dRow[ "TheCount "]   =   1;
dRow[ "TotalPrice "]   =   thePrice;
dtb.Rows.Add(dRow);
}
Session[ "myCar "]   =   dtb;
}
}
Response.Redirect( "myCar.aspx ");
}

------解决方案--------------------
好长的代码，加点注释会好看一些……