CODEWITHSUNDEEP
c#data-binding
Ahmed Sharkawy
Ahmed Sharkawy

Reputation: 193

Fill Combobox from database

I have an error with a combobox

My code:

SqlConnection conn = new SqlConnection();
try
{
    conn = new SqlConnection(@"Data Source=SHARKAWY;Initial Catalog=Booking;Persist Security Info=True;User ID=sa;Password=123456");
    string query = "select FleetName, FleetID from fleets";
    SqlCommand cmd = new SqlCommand(query, conn);
    cmd.CommandText = query;
    conn.Open();
    SqlDataReader drd = cmd.ExecuteReader();
    while (drd.Read())
    {
         cmbTripName.Items.Add(drd["FleetName"].ToString());
         cmbTripName.ValueMember = drd["FleetID"].ToString();
         cmbTripName.DisplayMember = drd["FleetName"].ToString();
    }
}
catch
{
     MessageBox.Show("Error ");
}

The data is presented in the combobox, but when you change the selection valuemember the displaymember does not change.

It's working now but when I click the button to show the data

private void button1_Click(object sender, EventArgs e)
{
    label1.Text = cmbTripName.DisplayMember;
    label2.Text = cmbTripName.ValueMember;
}

This is displayed:

FleetName
FleetID

It does not display the value

Upvotes: 13

Views: 164924

Answers (9)

Hein Lin Htun
Hein Lin Htun

Reputation: 1

You should use like this

private void button1_Click(object sender, EventArgs e)
{
    label1.Text = cmbTripName.Text;
    label2.Text = cmbTripName.SelectedValue.ToString();
}

Upvotes: 0

Beshoy Nady
Beshoy Nady

Reputation: 23

Try this:

  1.  

    using MySql.Data.MySqlClient;

  2. Write that:

    MySqlConnection con = new MySqlConnection("datasource=172.16.2.104;port=3306;server=localhost;database=DB_Name;uid=root;password=DB_Password;sslmode=none;charset=utf8;");
MySqlCommand cmd = new MySqlCommand();

var query2 = "SELECT `salary` FROM `employees_db` ";
using (var command2 = new MySqlCommand(query2, con))
{
    using (var reader2 = command2.ExecuteReader())
    {
        while (reader2.Read())
        {
            combox.Text  = reader2.GetString("salary");
        }
    }
}

Upvotes: 0

Inaldi Gomez
Inaldi Gomez

Reputation: 19

string query = "SELECT column_name FROM table_name";      //query the database
SqlCommand queryStatus = new SqlCommand(query, myConnection);
sqlDataReader reader = queryStatus.ExecuteReader();                               
            
while (reader.Read())   //loop reader and fill the combobox
{
ComboBox1.Items.Add(reader["column_name"].ToString());
}

Upvotes: 0

shakur oussama
shakur oussama

Reputation: 31

void Fillcombobox()
{

    con.Open();
    cmd = new SqlCommand("select ID From Employees",con);
    Sdr = cmd.ExecuteReader();
    while (Sdr.Read())
    {
        for (int i = 0; i < Sdr.FieldCount; i++)
        {
           comboID.Items.Add( Sdr.GetString(i));

        }
    }
    Sdr.Close();
    con.Close();

}

Upvotes: 3

Md.Rajibuzzaman
Md.Rajibuzzaman

Reputation: 1

private void StudentForm_Load(object sender, EventArgs e)

{
         string q = @"SELECT [BatchID] FROM [Batch]"; //BatchID column name of Batch table
         SqlDataReader reader = DB.Query(q);

         while (reader.Read())
         {
             cbsb.Items.Add(reader["BatchID"].ToString()); //cbsb is the combobox name
         }
  }

Upvotes: 0

user4481744
user4481744

Reputation: 11

            SqlConnection conn = new SqlConnection(@"Data Source=TOM-PC\sqlexpress;Initial Catalog=Northwind;User ID=sa;Password=xyz") ;
            conn.Open();
            SqlCommand sc = new SqlCommand("select customerid,contactname from customers", conn);
            SqlDataReader reader;

            reader = sc.ExecuteReader();
            DataTable dt = new DataTable();
            dt.Columns.Add("customerid", typeof(string));
            dt.Columns.Add("contactname", typeof(string));
            dt.Load(reader);

            comboBox1.ValueMember = "customerid";
            comboBox1.DisplayMember = "contactname";
            comboBox1.DataSource = dt;

            conn.Close();

Upvotes: 1

Nattrass
Nattrass

Reputation: 1313

To use the Combobox in the way you intend, you could pass in an object to the cmbTripName.Items.Add method.

That object should have FleetID and FleetName properties:

while (drd.Read())
{
    cmbTripName.Items.Add(new Fleet(drd["FleetID"].ToString(), drd["FleetName"].ToString()));
}
cmbTripName.ValueMember = "FleetId";
cmbTripName.DisplayMember = "FleetName";

The Fleet Class:

class Fleet
{
     public Fleet(string fleetId, string fleetName)
     {
           FleetId = fleetId;
           FleetName = fleetName
     }
     public string FleetId {get;set;}
     public string FleetName {get;set;}
}

Or, You could probably do away with the need for a Fleet class completely by using an anonymous type...

while (drd.Read())
{
    cmbTripName.Items.Add(new {FleetId = drd["FleetID"].ToString(), FleetName = drd["FleetName"].ToString()});
}
cmbTripName.ValueMember = "FleetId";
cmbTripName.DisplayMember = "FleetName";

Upvotes: 8

Pilgerstorfer Franz
Pilgerstorfer Franz

Reputation: 8359

You will have to completely re-write your code. DisplayMember and ValueMember point to columnNames! Furthermore you should really use a using block - so the connection gets disposed (and closed) after query execution.

Instead of using a dataReader to access the values I choosed a dataTable and bound it as dataSource onto the comboBox.

using (SqlConnection conn = new SqlConnection(@"Data Source=SHARKAWY;Initial Catalog=Booking;Persist Security Info=True;User ID=sa;Password=123456"))
{
    try
    {
        string query = "select FleetName, FleetID from fleets";
        SqlDataAdapter da = new SqlDataAdapter(query, conn);
        conn.Open();
        DataSet ds = new DataSet();
        da.Fill(ds, "Fleet");
        cmbTripName.DisplayMember =  "FleetName";
        cmbTripName.ValueMember = "FleetID";
        cmbTripName.DataSource = ds.Tables["Fleet"];
    }
    catch (Exception ex)
    {
        // write exception info to log or anything else
        MessageBox.Show("Error occured!");
    }               
}

Using a dataTable may be a little bit slower than a dataReader but I do not have to create my own class. If you really have to/want to make use of a DataReader you may choose @Nattrass approach. In any case you should write a using block!

EDIT

If you want to get the current Value of the combobox try this

private void cmbTripName_SelectedIndexChanged(object sender, EventArgs e)
{
    if (cmbTripName.SelectedItem != null)
    {
        DataRowView drv = cmbTripName.SelectedItem as DataRowView;

        Debug.WriteLine("Item: " + drv.Row["FleetName"].ToString());
        Debug.WriteLine("Value: " + drv.Row["FleetID"].ToString());
        Debug.WriteLine("Value: " + cmbTripName.SelectedValue.ToString());
    }
}

Upvotes: 23

Prasanna
Prasanna

Reputation: 4703

Out side the loop, set following.

cmbTripName.ValueMember = "FleetID"
cmbTripName.DisplayMember = "FleetName"

Upvotes: 1

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