Error C#: Object Reference Not Set To an Instance Object?

I create code for retrieve data from mysql (string and longblob), but i can't see the errors in my code.

can you help me to fix this? I am using mysql (longblob) and retrieve image to picturebox.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.Odbc;
using System.IO;
namespace csharp_report
{
public partial class frmMain : Form
{
public frmMain()
{
InitializeComponent();
}
OdbcConnection CONN;
OdbcCommand CMD;
DataSet DS;
OdbcDataAdapter DA;
OdbcDataReader DR;
String LokasiData;
public void Koneksi()
{
LokasiData = "Driver={MySQL ODBC 5.3 ANSI Driver};database=visualbasic_report;server=localhost;uid=root;pwd=";
CONN = new OdbcConnection(LokasiData);
if (CONN.State == ConnectionState.Closed)
{
CONN.Open();
}
}
public void TampilGrid()
{
Koneksi();
OdbcDataAdapter DA = new OdbcDataAdapter("select * from report", CONN);
DataSet DS = new DataSet();
DA.Fill(DS, "report");
DataGridView1.DataSource = DS.Tables["report"];
DataGridView1.ReadOnly = true;
}
public void TampilKembali()
{
try
{
CONN.Open();
CMD.Connection = CONN;
CMD.CommandType = CommandType.Text;
CMD.CommandText = "Select * from report where kode='" + txtKode.Text + "'";
DR = CMD.ExecuteReader();
if (DR.HasRows)
{
DR.Read();
txtNama.Text = DR["nama"].ToString();
txtAlamat.Text = DR["alamat"].ToString();
txtPekerjaan.Text = DR["pekerjaan"].ToString();
byte[] data = (byte[])DR["foto"];
MemoryStream ms = new MemoryStream(data);
ptbFoto.BackgroundImage = Image.FromStream(ms);
ptbFoto.BackgroundImageLayout = ImageLayout.Stretch;
DR.Close();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
//throw;
}
}
private void DataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewRow row;
row = DataGridView1.CurrentRow;
txtKode.Text = row.Cells["kode"].Value.ToString();
CONN.Close();
TampilKembali();
}
private void frmMain_Load(object sender, EventArgs e)
{
TampilGrid();
}
private void btnReport_Click(object sender, EventArgs e)
{
String sTitle;
sTitle = txtKode.Text;
View frm = new View(sTitle);
frm.Show();
}
}
}

3 Replies

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Nanddeep Nachan8y ago
Make sure all your objects have been initialized first before invoking any methods on it
Nitin Sontakke8y ago
Do not declare variables at the class level. Not a very good practise. You are defeating the whole purpose of object oriented programing.
Manav Pandya8y ago
Hello

Which line you getting error , so that we can help you easily

And also provide message you have caught in catch block

Thanks