Question

我在c＃中有一个datagridview，我从mysql数据库填充。用户查看信息，然后将其保存到不同的mysql数据库。我知道两个工作的连接和我的标题之间的连接说我在for循环的第一个字符串上得到一个空例外。

行中只有6列，我唯一能想到的是我正在查看行而不是列，但不确定代码应该是什么编辑我将其更改为大部分曾对<而不是<=说过，我知道为什么我会收到错误，但不知道如何获取我需要的信息。错误来自于即使单元格中存在值，单元格显示为null的事实。

string ConnectionString2 = ConfigurationSettings.AppSettings["ConnectionString2"];
MySqlConnection connection2;
connection2 = new MySqlConnection(ConnectionString2);

int i;
for (i = 0; i < dataGridView1.Rows.Count; i++)
{
    string day = dataGridView1.Rows[i].Cells[0].Value.ToString();
    string Desc = dataGridView1.Rows[i].Cells[1].Value.ToString();
    string item = dataGridView1.Rows[i].Cells[2].Value.ToString();
    string prod = dataGridView1.Rows[i].Cells[3].Value.ToString();
    string vol = dataGridView1.Rows[i].Cells[4].Value.ToString();
    string qty = dataGridView1.Rows[i].Cells[5].Value.ToString();

    MySqlCommand cmdwk = new MySqlCommand("INSERT INTO spt_proposal_line_lab (proposal_Id,day_Name,proposal_Desc,proposal_Vol,product_Id,proposal_Qty,item_Id) VALUES (@propid,@day,@desc,@vol,@prod,@qty,@item)", connection2);
    MySqlParameter propid = new MySqlParameter("@propid", b);
    MySqlParameter day1 = new MySqlParameter("@day", day);
    MySqlParameter Desc1 = new MySqlParameter("@desc", Desc);
    MySqlParameter vol1 = new MySqlParameter("@vol", vol);
    MySqlParameter prod1 = new MySqlParameter("@prod", prod);
    MySqlParameter qty1 = new MySqlParameter("@qty", qty);
    MySqlParameter item1 = new MySqlParameter("@item", item);

    cmdwk.Parameters.Add(day1);
    cmdwk.Parameters.Add(propid);
    cmdwk.Parameters.Add(Desc1);
    cmdwk.Parameters.Add(prod1);
    cmdwk.Parameters.Add(vol1);
    cmdwk.Parameters.Add(qty1);
    cmdwk.Parameters.Add(item1); 
}

调用datagrid并在按钮中填充此负载编辑看到我离我的img post能力有一点点我会尝试更多地解释这一点单击该按钮并运行此代码时，错误出现在

string day = dataGridView1.Rows[i].Cells[0].Value.ToString();

错误是

Object reference not set to an instance of an object.

System.NullReferenceException was unhandled
  HResult=-2147467261
   Message=Object reference not set to an instance of an object.
    Source=SpectLabRemake2
    StackTrace:
   at SpectLabRemake2.Form6.btn_Save_Click(Object sender, EventArgs e)

Answer 1

我认为就是这条线：

for (i = 0; i <= dataGridView1.Rows.Count; i++)

你走得太远了。尝试：

for (i = 0; i < dataGridView1.Rows.Count; i++)

Answer 2

对于遇到此问题的每个人，我会发布修复此问题的代码，并且非常感谢那些对此问题很有帮助的人。

  for (i = 0; i < dataGridView1.Rows.Count-1; i++)
        {

            string ConnectionString2 = ConfigurationSettings.AppSettings["ConnectionString2"];
            MySqlConnection connection2;








            connection2 = new MySqlConnection(ConnectionString2);
            connection2.Open();


                string day = dataGridView1.Rows[i].Cells[0].Value.ToString();
                string Desc = dataGridView1.Rows[i].Cells[1].Value.ToString();
                string item = dataGridView1.Rows[i].Cells[2].Value.ToString();
                string prod = dataGridView1.Rows[i].Cells[3].Value.ToString();
                string vol = dataGridView1.Rows[i].Cells[4].Value.ToString();
                string qty = dataGridView1.Rows[i].Cells[5].Value.ToString();


                MySqlCommand cmdwk = new MySqlCommand("INSERT INTO spt_proposal_line_lab (proposal_Id,day_Name,proposal_Desc,proposal_Vol,product_Id,proposal_Qty,item_Id) VALUES (@propid,@day,@desc,@vol,@prod,@qty,@item)", connection2);
                MySqlParameter propid = new MySqlParameter("@propid", b);
                MySqlParameter day1 = new MySqlParameter("@day", day);
                MySqlParameter Desc1 = new MySqlParameter("@desc", Desc);
                MySqlParameter vol1 = new MySqlParameter("@vol", vol);
                MySqlParameter prod1 = new MySqlParameter("@prod", prod);
                MySqlParameter qty1 = new MySqlParameter("@qty", qty);
                MySqlParameter item1 = new MySqlParameter("@item", item);

                cmdwk.Parameters.Add(day1);
                cmdwk.Parameters.Add(propid);
                cmdwk.Parameters.Add(Desc1);
                cmdwk.Parameters.Add(prod1);
                cmdwk.Parameters.Add(vol1);
                cmdwk.Parameters.Add(qty1);
                cmdwk.Parameters.Add(item1);
                cmdwk.ExecuteNonQuery();



            }
        }

    }
}

布伦特

从gridview插入mysql获取null异常

2 个答案: