some couple of errors in billing system

Hello guyz,

Please i need codes and solution on how to resolve this errors in my simple billing system

Many thanks.

codes

namespace NSPM_Sales_Invoice
{
public partial class UpdateBill : Form
{
SqlConnection con = new SqlConnection(Properties.Settings.Default.NSPM_Sales_InvoiceCon);
SqlCommand cmd;
SqlDataAdapter da;
DataTable dt;
public UpdateBill()
{
InitializeComponent();
}
private void UpdateBill_Load(object sender, EventArgs e)
{
con.Open();
cmd = con.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "Select * From Tbl_RowData where JobNo like ('" + txtJobNo.Text + "%')";
cmd.ExecuteNonQuery();
dt = new DataTable();
da = new SqlDataAdapter(cmd);
da.Fill(dt);
dataGridView1.DataSource = dt;
con.Close();
dataGridView1.Columns[1].AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill;
// Fill description form table to descrption combobox
cmbDescription.Select();
cmbDescription.Items.Clear();
con.Open();
cmd = con.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "Select ProName from tbl_Products order by ProName asc";
cmd.ExecuteNonQuery();
dt = new DataTable();
da = new SqlDataAdapter(cmd);
da.Fill(dt);
foreach (DataRow dr in dt.Rows)
{
cmbDescription.Items.Add(dr["ProName"].ToString());
}
con.Close();
}
private void txtUnitPrice_Leave(object sender, EventArgs e)
{
CalGoodValue();
}
public void CalGoodValue()
{
double a1, b1, i;
double.TryParse(txtUnitPrice.Text, out a1);
double.TryParse(txtQuantity.Text, out b1);
i = a1 * b1;
if (1 > 0)
{
txtGoodValue.Text = i.ToString("C").Remove(0, 1);
}
}
private void txtQuantity_Leave(object sender, EventArgs e)
{
CalGoodValue();
}
private void LoadSerialNo()
{
int i = 1;
foreach (DataGridViewRow row in dataGridView1.Rows)
{
row.Cells[0].Value = i; i++;
}
}
private void dataGridView1_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
{
LoadSerialNo();
}
int i;
private void dataGridView1_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
{
i = e.RowIndex;
DataGridViewRow row = dataGridView1.Rows[i];
txtDeleteUpdate.Text = row.Cells[0].Value.ToString();
cmbDescription.Text = row.Cells[1].Value.ToString();
txtQuantity.Text = row.Cells[2].Value.ToString();
txtUnitPrice.Text = row.Cells[3].Value.ToString();
txtGoodValue.Text = row.Cells[4].Value.ToString();
}
private void btnDelete_Click(object sender, EventArgs e)
{
foreach (DataGridViewRow row in dataGridView1.SelectedRows)
{
if (!row.IsNewRow) dataGridView1.Rows.Remove(row);
LoadSerialNo();
}
}
private void btnAdd_Click(object sender, EventArgs e)
{
//if txxtDeleteUpdate textbox is empty then add newrow else Update Selected row
if (txtDeleteUpdate.Text == "")
{
for (int i = 0; i < dataGridView1.Rows.Count - 1; i++)
{
dataGridView1.Rows[1].Cells[1].Value = (i + 1).ToString();
}
DataTable dt = dataGridView1.DataSource as DataTable;
DataRow row1 = dt.NewRow();
row1[1] = cmbDescription.Text.ToString();
row1[2] = txtQuantity.Text.ToString();
row1[3] = txtUnitPrice.Text.ToString();
Arow1[4] = txtGoodValue.Text.ToString();
row1[5] = txtCustomer.Text.ToString();
row1[6] = txtJobNo.Text.ToString();
cmbDescription.Focus();
dt.Rows.Add(row1);
}
else
{
DataGridViewRow row = dataGridView1.Rows[i];
row.Cells[1].Value = cmbDescription.Text;
row.Cells[2].Value = txtQuantity.Text;
row.Cells[3].Value = txtUnitPrice.Text;
row.Cells[4].Value = txtGoodValue.Text;
row.Cells[5].Value = txtCustomer.Text;
row.Cells[6].Value = txtJobNo.Text;

ERROR 2

codes

namespace NSPM_Sales_Invoice
{
public partial class Dashboard : Form
{
public Dashboard()
{
InitializeComponent();
}
private void productsToolStripMenuItem_Click(object sender, EventArgs e)
{
Products p = new Products();
p.MdiParent = this;
p.Show();
}
private void newToolStripMenuItem_Click(object sender, EventArgs e)
{
frmNewBill nb = new frmNewBill();
nb.MdiParent = this;
nb.Show();
}
private void viewBillsToolStripMenuItem_Click(object sender, EventArgs e)
{
ViewBills vb = new ViewBills();
vb.MdiParent = this;
vb.Show();
}

ERROR 3

namespace NSPM_Sales_Invoice
{
static class Program
{
///
/// The main entry point for the application.
///
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Login());
}

namespace NSPM_Sales_Invoice
{
public partial class Login : Form
{
public Login()
{
InitializeComponent();
}
private void Login_Load(object sender, EventArgs e)
{
}
private void btnLogin_Click(object sender, EventArgs e)
{
SqlConnection sqlcon = new SqlConnection(@"Data Source=Chidiebere;Initial Catalog=NSPM_Sales_Invoice_DB;Integrated Security=True");
String query = "Select * from tbl_Login Where username = '" + txtUserName.Text.Trim() + "' and password = '" + txtPassword.Text.Trim() + "'";
SqlDataAdapter sda = new SqlDataAdapter(query, sqlcon);
DataTable dtbl = new DataTable();
sda.Fill(dtbl);
if (dtbl.Rows.Count == 1)
{
Dashboard objDashboard = new Dashboard();
this.Hide();
objDashboard.Show();
}
else
{
MessageBox.Show("Check your Username and Password");
}
}
private void btnExit_Click(object sender, EventArgs e)
{
this.Close();
}
}
}

5 Replies

Know the answer? Post it — somebody with the same question will find it here.

Amit Gupta6y ago
Hey

First of all, use column names instead of index, it wil cause problem whenever you want to re-arrange or add/delete any column

Replace
DataRow row1 = dt.NewRow();
row1[1] = cmbDescription.Text.ToString();
row1[2] = txtQuantity.Text.ToString();
....
cmbDescription.Focus();
With like
DataRow row1 = dt.NewRow();
row1["Description"] = cmbDescription.Text); //therer is not need to use ToString(), as ..Text is already a string datatype // .ToString();
row1["Qty"] = Convert.ToInt32(txtQuantity.Text); // Convert string to int
...
cmbDescription.Focus();
Do change the insert the appropriate datatype matching with the database column

Clean and Rebuild your project
+2
Chidiebere Mgbemena6y ago
How can I send the project to your email to run? I am using visual studio 2015 and SQL 2014. Thanks
0
Salman Beg6y ago
object reference not set to an instance of an object means somewhere the object is null. From here I can't tell you in which line exactly the error is because I can't debug the code from here. Thanks
0
Chidiebere Mgbemena6y ago
Salman I have checked I can't see the line in my code where I assigned string values that is causing the error. Please help me find if. Thanks
0
Salman Beg6y ago
Hey, input string was not in a correct format means in database column you are taking datatype as int but in the code you are assigning string value into it. You should pass int value otherwise you need to convert string to int. For object reference not set to an instance of an object you need to debug each and every line and need to check where it is getting null because from here it is very hard to tell you. Follow this video for input string was not in a correct format as example, https://youtu.be/32Y_mHwD01U
+2