求指教：为什么以下代码，当datagridview有N行数据时，它只添加一行数据到数据库里，我看不出有什么错漏，其中Base_Class.DataBase.Insert(sql);是一个添加方法

            this.dataGridView1.AllowUserToAddRows = false;
            for (int i = 0; i < dataGridView1.Rows.Count; i++)
            {
               string sql = "insert into tb_DanJu (DanJuHao,DanWeiQuanCheng,DanWeiLeiBie,YuanShiDanHao,ShiJian,CaiWuNianYue,KuFang,JingShouRen,ZhiDanRen,DanJuBeiZhu) values('" + textBox1.Text.Trim() + "','" + textBox4.Text.Trim() + "','" + label9.Text.Trim() + "','" + textBox2.Text.Trim() + "','" + System.DateTime.Now.ToString("yyyy-MM-dd hh:mm:ss") + "','" + Base_Class.BaseInfo.dangqianriqi + "','" + comboBox3.Text.Trim() + "','" + comboBox1.Text.Trim() + "','" + textBox3.Text.Trim() + "','" + "无" + "')";
               Base_Class.DataBase.Insert(sql);
            }