Prevent Combobox values repeating When select Items form another combobox

Question

I have two combo box which names are cmbInvoiceNo and cmbItemName. I get all invoice numbers to the cmbInvoiceNo using following code.

// Get data from database to the **cmbInvoiceNo** combobox
    private void GetInvoiceNo()
    {
        using (SqlConnection con = new SqlConnection(CS))
        {
            con.Open();
            SqlCommand cmd = new SqlCommand("Select InvoiceNo From tblInvoice GROUP BY InvoiceNo", con);
            SqlDataReader dr = cmd.ExecuteReader();

            while (dr.Read())
            {
                string invoiceNo = dr.GetString(0);
                cmbInvoiceNo.Items.Add(invoiceNo);
            }
        }
    }

After that when I change the Invoice Numbers in cmbInvoiceNo combobox, my another combobox (cmbItemName) show items names according to the InvoiceNo. I set it to cmbInvoiceNo_SelectedIndexChanged event like this.

private void cmbInvoiceNo_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (cmbInvoiceNo.SelectedIndex == 0)
        {
            ClearAllFields();
        }

        using (SqlConnection con = new SqlConnection(CS))
        {
            SqlCommand cmd = new SqlCommand("SELECT ItemName from tblInvoice where InvoiceNo = '" + cmbInvoiceNo.Text + "'", con);
            con.Open();
            cmd.ExecuteNonQuery();
            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                string itemName = (string)dr["ItemName"].ToString();
                cmbItemNames.Items.Add(itemName);                 
            }
        }
    }

It also working as expected. But my problem is after selected one invoice number I get all item names into cmbItemName combobox. When I select another Invoice Number my cmbItemName combox box show items with previous selected items. Its mean cmbItemName combo box repeat values. Can you please tell me how to show Items name without repeating item name. I want to show item name according to the invoiceNo. When invoiceNo change all item show is another combobox without prevoice value or repeat. Thank you. Please tell me how to avoid this problem.

score 0 · Answer 1 · answered Feb 03 '21 at 16:07

0

Shouldn't it ben selectesindex ==-1? No Selected row.

answered Feb 03 '21 at 16:07

Ann

1
2

Can you please send me full code. Your answer is not clear for me. – sandanuwan dharmarathna Feb 03 '21 at 16:09
Can you just clear all items from the cmbItemNames before adding new ones? – Natalia Muray Feb 03 '21 at 16:16
@NataliaMuray . No have any idea how to do it. Can you send me code. When I select item second time my second combo box value is repeat with new value and previous value. that that's problem – sandanuwan dharmarathna Feb 03 '21 at 16:21
@NataliaMuray Thank you vary much. Its working as expected after I send it with clear(); Thanks again ok. – sandanuwan dharmarathna Feb 03 '21 at 16:28

score 0 · Accepted Answer · answered Feb 03 '21 at 16:30

0

Seems like

cmbItemNames.Items.Clear();

before adding items is the solution here

answered Feb 03 '21 at 16:30

Natalia Muray

252
1
6

Prevent Combobox values repeating When select Items form another combobox

2 Answers2