I have a combobox which is called combobox2, which I want to populate with the content of the column of a table called "bulkinput". Any ideas?

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I need to be able to copy the contents of a table field (column) into a combobox so that a user can select directly from there without me entering the combobox values during its design

What I have tried:

private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                SqlConnection bscn = new SqlConnection("Data Source=PV10\\LOCALSERVER;Initial Catalog=SmallSoftwareDB;Integrated Security=True;Pooling=False");
                string ins = "insert into BulkSale(ProductSource, Date, Quantity, Type, UnitPrice, Total) values('" + textBox2.Text + "', '" + dateTimePicker1.Value + "', '" + textBox3.Text + "', '" + comboBox1.Text + "', '" + textBox4.Text + "', '" + textBox5.Text + "' )";
                string sPN = "select ProductName from BulkInput";
                SqlCommand P = new SqlCommand(sPN, bscn);
                comboBox2.DataSource = P.BeginExecuteReader();
                SqlCommand scmd = new SqlCommand(ins, bscn);
                bscn.Open();
                scmd.ExecuteNonQuery();
                MessageBox.Show("Successfully Completed.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                bscn.Close();
            }
            catch (Exception exc)
            {
                MessageBox.Show(exc.Message, " ", MessageBoxButtons.OKCancel, MessageBoxIcon.Warning);
            }
        }

Posted 17-Sep-16 4:08am

Nganku Junior

Updated 19-Sep-16 0:00am

Karthik_Mahalingam

v2

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2 solutions

Solution 2

C#

try
           {
               using (SqlConnection con = new SqlConnection(ConString))
               {
                   SqlConnection con = new SqlConnection(CS);
                   con.Open();
                   string str = "SELECT ProductName FROM BulkInput";
                   cmd = new SqlCommand(str, con);
                   DataTable dTable = new DataTable();
                   DataRow dr;
                   SqlDataAdapter da = new SqlDataAdapter(cmd);
                   da.Fill(dTable);

                   //if you want to insert or validate as '--select--' text in your first index of ComboBox
                   dr = dTable.NewRow();
                   dr.ItemArray = new object[] { 0, "--Select--" };
                   dTable.Rows.InsertAt(dr, 0);

                   yourComboBox.DisplayMember = dTable.Columns["ProductName"].ToString();
                   yourComboBox.ValueMember = dTable.Columns["ID"].ToString();
                   yourComboBox.DataSource = dTable;
               }
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
           }

Always try to keep the connection string inside the configuration file (app.config).
And never concatenate strings to form an SQL command. you leave your code wide open to SQL Injection. Always use a parameterised query or stored procedure.

Posted 19-Sep-16 0:00am

Muhammad Rehbar Sheikh

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OriginalGriff · Accepted Answer · 2016-09-17T04:24:00

For starters, don't do it like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

Second, You need to open the connection before you try to use the reader.

Third, don't use a DataReader - they need everything alive while they are running, and your connection is closed before the combobox can load. Use a DataAdapter and a DataTable instead:

try
    {
    using (SqlConnection con = new SqlConnection(strConnect))
        {
        con.Open();
        using (SqlCommand cmd = new SqlCommand("SELECT ProductName FROM BulkInput", con))
            {
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                DataTable dt = new DataTable();
                da.Fill(dt);
                myComboBox.DataSource = dt;
                myComboBox.DisplayMember = "ProductName";
                }
            }
        }
    }
catch (Exception ex)
    {
    MessageBox.Show(ex.Message);
    }

Always try to keep the connection string inside the configuration file (app.config or web.config, in your case it will be app.config). Say, if you have the key named as "conn" in the config file, you can fetch the value as below

string strConnect = ConfigurationManager.ConnectionStrings["conn"].ToString();