从Excel中获取数据到datagridview时，第三个Cell数据（lname）未显示在Datagridview上。 [英] While fetching data from Excel to datagridview third Cell data(lname) not displayed on Datagridview..

问题描述

private void Upload_Excel_click(object sender, EventArgs e)
    {
// For Uploading Excel file From Computer
        int count = 0;
        string[] FilenameName;
        foreach (string item in openFileDialog1.FileNames)
        {
            FilenameName = item.Split('\\');
            File.Copy(item, @"Images\" + FilenameName[FilenameName.Length - 1]);
            count++;
        }
//for storing data from Excel to datagridview
        System.Data.OleDb.OleDbConnection MyConnection;
        System.Data.DataSet DtSet;
        System.Data.OleDb.OleDbDataAdapter MyCommand;
        MyConnection = new System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source='D:\\Edbeans Windows App Modified\\Edbeans Windows App\\Project\\Registration\\bin\\Debug\\Images\\Book1.xlsx';Extended Properties=\"Excel 12.0 Xml;HDR=YES;IMEX=1\";");
        MyCommand = new System.Data.OleDb.OleDbDataAdapter("select * from [Sheet1$]", MyConnection);
        MyCommand.TableMappings.Add("ams_records ", "temp_reg_details");
        DtSet = new System.Data.DataSet();
        MyCommand.Fill(DtSet);
        dataGridView1.DataSource = DtSet.Tables[0];
        MySqlConnection local_connection = myConnection.getConnection();
        local_connection.Open();
        string str = this.dataGridView1.Rows.Count.ToString();
        int num = int.Parse(str);
        for (int row = 0; row < num - 1; row++)
        {

            string query = "INSERT INTO temp_reg_details(fname, mname, lname, class_code,guard_fname,guard_mname,guard_lname,guard_mob_no,guard_email,rfid_cardNo,rfid_password) VALUES (@fname, @mname, @lname, @class_code, @guard_fname, @guard_mname, @guard_lname, @guard_mob_no, @guard_email, @rfid_cardNo, @rfid_password)";
            MySqlCommand cmd = new MySqlCommand(query, local_connection);
            cmd.Parameters.AddWithValue(
                    "@fname", dataGridView1.Rows[row].Cells[1].Value.ToString());
            cmd.Parameters.AddWithValue(
                "@mname", dataGridView1.Rows[row].Cells[2].Value.ToString());
//Its shows error of NullrefereceException was unhandled(Object reference not set to an instance of an object.) while fetching data from 3rd cell
            cmd.Parameters.AddWithValue(
                 "@lname", dataGridView1.Rows[row].Cells[3].Value.ToString());
//below are working fine
            cmd.Parameters.AddWithValue(
                "@class_code", dataGridView1.Rows[row].Cells[4].Value.ToString());
            cmd.Parameters.AddWithValue(
               "@guard_fname", dataGridView1.Rows[row].Cells[5].Value.ToString());
            cmd.Parameters.AddWithValue(
               "@guard_mname", dataGridView1.Rows[row].Cells[6].Value.ToString());
            cmd.Parameters.AddWithValue(
               "@guard_lname", dataGridView1.Rows[row].Cells[7].Value.ToString());
            cmd.Parameters.AddWithValue(
               "@guard_mob_no", dataGridView1.Rows[row].Cells[8].Value.ToString());
            cmd.Parameters.AddWithValue(
               "@guard_email", dataGridView1.Rows[row].Cells[9].Value.ToString());
            cmd.Parameters.AddWithValue(
               "@rfid_cardNo", dataGridView1.Rows[row].Cells[10].Value.ToString());
            cmd.Parameters.AddWithValue(
               "@rfid_password", dataGridView1.Rows[row].Cells[11].Value.ToString());
            cmd.ExecuteNonQuery();
            cmd.Parameters.Clear(); //for proper looping 
        }
        MessageBox.Show("sucess");
        local_connection.Close();

    }

推荐答案

，MyConnection）;
MyCommand.TableMappings。添加（ ams_records， < span class =code-string> temp_reg_details）;
DtSet = new System.Data.DataSet（）;
MyCommand.Fill（DtSet）;
dataGridView1.DataSource = DtSet.Tables [ 0 ];
MySqlConnection local_connection = myConnection.getConnection（）;
local_connection.Open（）;
string str = 此 .dataGridView1.Rows。 Count.ToString（）;
int num = int .Parse（str）;
for （ int row = 0 ; row < num - 1 ;行++）
{

string query = INSERT INTO temp_reg_details（fname，mname，lname，class_code，guard_fname，guard_mname，guard_lname，guard_mob_no，guard_email，rfid_cardNo，rfid_password）VALUES（@ fname，@ mname，@ lname，@ class_code，@ guard_fname， @guard_mname，@ guard_lname，@ guard_mob_no，@ guard_email，@ rfid_cardNo，@ rfid_password）;
MySqlCommand cmd = new MySqlCommand（query，local_connection）;
cmd.Parameters.AddWithValue（
@ fname，dataGridView1.Rows [row] .Cells [ 1 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ mname，dataGridView1.Rows [row] .Cells [ 2 ]。Value.ToString（））;
// 它显示NullrefereceException错误未处理（对象引用未设置为实例对象。）从第三个单元格中获取数据
cmd.Parameters.AddWithValue（
@ lname，dataGridView1.Rows [row] .Cells [ 3 ]。Value.ToString（））;
// 以下工作正常
cmd .Parameters.AddWithValue（
@ class_code，dataGridView1.Rows [row] .Cells [ 4 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ guard_fname，dataGridView1.Rows [row] .Cells [ 5 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ guard_mname，dataGridView1.Rows [row] .Cells [ 6 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ guard_lname，dataGridView1.Rows [row] .Cells [ 7 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ guard_mob_no，dataGridView1.Rows [row] .Cells [ 8 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ guard_email，dataGridView1.Rows [row] .Cells [ 9 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ rfid_cardNo，dataGridView1.Rows [row] .Cells [ 10 ]。Value.ToString（））;
cmd.Parameters.AddWithValue（
@ rfid_password，dataGridView1.Rows [row] .Cells [ 11 ]。Value.ToString（））;
cmd.ExecuteNonQuery（）;
cmd.Parameters.Clear（）; // 正确循环
}
MessageBox.Show（ sucess）;
local_connection.Close（）;

}

", MyConnection); MyCommand.TableMappings.Add("ams_records ", "temp_reg_details"); DtSet = new System.Data.DataSet(); MyCommand.Fill(DtSet); dataGridView1.DataSource = DtSet.Tables[0]; MySqlConnection local_connection = myConnection.getConnection(); local_connection.Open(); string str = this.dataGridView1.Rows.Count.ToString(); int num = int.Parse(str); for (int row = 0; row < num - 1; row++) { string query = "INSERT INTO temp_reg_details(fname, mname, lname, class_code,guard_fname,guard_mname,guard_lname,guard_mob_no,guard_email,rfid_cardNo,rfid_password) VALUES (@fname, @mname, @lname, @class_code, @guard_fname, @guard_mname, @guard_lname, @guard_mob_no, @guard_email, @rfid_cardNo, @rfid_password)"; MySqlCommand cmd = new MySqlCommand(query, local_connection); cmd.Parameters.AddWithValue( "@fname", dataGridView1.Rows[row].Cells[1].Value.ToString()); cmd.Parameters.AddWithValue( "@mname", dataGridView1.Rows[row].Cells[2].Value.ToString()); //Its shows error of NullrefereceException was unhandled(Object reference not set to an instance of an object.) while fetching data from 3rd cell cmd.Parameters.AddWithValue( "@lname", dataGridView1.Rows[row].Cells[3].Value.ToString()); //below are working fine cmd.Parameters.AddWithValue( "@class_code", dataGridView1.Rows[row].Cells[4].Value.ToString()); cmd.Parameters.AddWithValue( "@guard_fname", dataGridView1.Rows[row].Cells[5].Value.ToString()); cmd.Parameters.AddWithValue( "@guard_mname", dataGridView1.Rows[row].Cells[6].Value.ToString()); cmd.Parameters.AddWithValue( "@guard_lname", dataGridView1.Rows[row].Cells[7].Value.ToString()); cmd.Parameters.AddWithValue( "@guard_mob_no", dataGridView1.Rows[row].Cells[8].Value.ToString()); cmd.Parameters.AddWithValue( "@guard_email", dataGridView1.Rows[row].Cells[9].Value.ToString()); cmd.Parameters.AddWithValue( "@rfid_cardNo", dataGridView1.Rows[row].Cells[10].Value.ToString()); cmd.Parameters.AddWithValue( "@rfid_password", dataGridView1.Rows[row].Cells[11].Value.ToString()); cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); //for proper looping } MessageBox.Show("sucess"); local_connection.Close(); }

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