Question

In my windows form i have two combobox and one text box when a jobecode is selected from cmbjobecode it will load cmbquotationcode with corresponding quotations and fills a textbox txtamount with amount of selected quotation

all is fine except i cannot get the textbox filled with the amount can anyone help in sorting mistake

 private void cmbjobcode_SelectedIndexChanged(object sender, EventArgs e)
        {
            comboQuotationboxload();
        }

public void comboQuotationboxload()
        {

            OleDbConnection oleDbConnection1 = new System.Data.OleDb.OleDbConnection(connString);
            oleDbConnection1.Open();

            OleDbCommand oleDbCommand1 = new System.Data.OleDb.OleDbCommand("Select quotationpk ,quotationcode , amount from  quotationmastertable  where jobpk = " + cmbjobcode.SelectedValue + "", oleDbConnection1);



            OleDbDataReader reader = oleDbCommand1.ExecuteReader();

            DataTable dt = new DataTable();
            dt.Columns.Add("quotationpk", typeof(int));
            dt.Columns.Add("quotationcode", typeof(string));
            dt.Columns.Add("amount", typeof(int));
            dt.Load(reader);
            cmbQuotationcode.ValueMember = "quotationpk";
            cmbQuotationcode.DisplayMember = "quotationcode";
            cmbQuotationcode.DataSource = dt.DefaultView;
            txtamount.text= "amount";


            oleDbConnection1.Close();

        }

Answer 1

create dt at class scope

DataTable dt = new DataTable();

/// Add columns to Table at Form_Load()

    dt.Columns.Add("quotationpk", typeof(int));
    dt.Columns.Add("quotationcode", typeof(string));
    dt.Columns.Add("amount", typeof(int));

//Then do fill operation

 private void cmbjobcode_SelectedIndexChanged(object sender, EventArgs e)
        {
            comboQuotationboxload();
        }

public void comboQuotationboxload()
        {

            OleDbConnection oleDbConnection1 = new System.Data.OleDb.OleDbConnection(connString);
            oleDbConnection1.Open();

            OleDbCommand oleDbCommand1 = new System.Data.OleDb.OleDbCommand("Select quotationpk ,quotationcode , amount from  quotationmastertable  where jobpk = " + cmbjobcode.SelectedValue + "", oleDbConnection1);



            OleDbDataReader reader = oleDbCommand1.ExecuteReader();

            dt.Load(reader);
            cmbQuotationcode.ValueMember = "quotationpk";
            cmbQuotationcode.DisplayMember = "quotationcode";
            cmbQuotationcode.DataSource = dt.DefaultView;



            oleDbConnection1.Close();

        }

//filter data and display in the text box

 private void cmbQuotationcode_SelectedIndexChanged(object sender, EventArgs e)
        {
            DataView dvDataTable = new DataView(dt);
dvDataTable.RowFilter = "quotationpk ='" + cmbQuotationcode.SelectedValue "'";
if(dvDataTable.Count > 0)
{
 txtamount.Text= Convert.ToString(dvDataTable["amount"]);
}
else
{ 
txtamount.Text = "0";
}
        }