for循环中赋值为何只有最后一次的值,如何得到所有值??

string sz = "";
string[] gs = new string[dt.Rows.Count];
for (int j = 0;j< gs.Length; j++) {
        sz = ""+
                "<tr><td>"+ dt.Rows[j]["goods_title"].ToString() + "</td>"+
                "<td>" + dt.Rows[j]["goods_price"].ToString() + "</td>"+
                "<td>" + dt.Rows[j]["quantity"].ToString() + "</td>"+
                "<td>" + Convert.ToDecimal(dt.Rows[j]["goods_price"].ToString())*Convert.ToInt32(dt.Rows[j]["quantity"].ToString()) + "</td></tr>" +
                "";
}
HtmlGenericControl h = new HtmlGenericControl("div");
h.InnerHtml = s + sz + se;
this.contentss.Controls.Add(h);

这个意思？

 sz += ""+
                "<tr><td>"+ dt.Rows[j]["goods_title"].ToString() + "</td>"+
                "<td>" + dt.Rows[j]["goods_price"].ToString() + "</td>"+
                "<td>" + dt.Rows[j]["quantity"].ToString() + "</td>"+
                "<td>" + Convert.ToDecimal(dt.Rows[j]["goods_price"].ToString())*Convert.ToInt32(dt.Rows[j]["quantity"].ToString()) + "</td></tr>" +
                "";