如何从SQL数据库中获取数据以存储到组合框中 - C＃

Question

How can i get the value of outlet ID it on a comboBox? here is my code to getting the values from Database and store it on a combobox.

public partial class Addstock : Form
{
    String connectionString = ConfigurationManager.ConnectionStrings["TCConnectionString"].ConnectionString;
    List<BOStockTransfer> StockList = new List<BOStockTransfer>();
    int updateIndex = -1;

    public Addstock()
    {
        InitializeComponent();
    }

    private void Addstock_Load(object sender, EventArgs e)
    {
        loadstock();
        GetOutlets();
        Getproduct();
        GetGetWH();
        cmdoutletID.Visible = false;
        lbloutid.Visible = false;
        cmdwh.Visible = false;
        lblwh.Visible = false;
    }

    private void GetOutlets()
    {


        BOStockTransfer obj_StockTransfer = new BOStockTransfer();
        DataSet ds_OutletList = obj_StockTransfer.GetOutlets(connectionString);

        if (ds_OutletList.Tables[0].Rows.Count != 0)
        {
            cmdoutletID.DataSource = ds_OutletList.Tables[0];
            cmdoutletID.DisplayMember = "outletId";
        }

    }

Thank you for your help!

Answer 1

you are setting :

cmdoutletID.Visible = false;

what makes the combobox invisible

you have to set it as follows :

cmdoutletID.Visible = true;

After you added the images , the column name is outletID and Not outletId so change your code as follows :

private void GetOutlets()
    {
    BOStockTransfer obj_StockTransfer = new BOStockTransfer();
    DataSet ds_OutletList = obj_StockTransfer.GetOutlets(connectionString);

    if (ds_OutletList.Tables[0].Rows.Count != 0)
    {
        cmdoutletID.DataSource = ds_OutletList.Tables[0];
        cmdoutletID.DisplayMember = "outletID";
        cmdoutletID.ValueMember = "outletID";
        cmdoutletID.Enabled = true;

    }

}

Answer 2

The combo box has two properties which determine where it loads data from:

DisplayMember

ValueMember

The "ValueMember" property defines which named field populates the ListItem's "ValueProperty". That way, when you do combobox.SelectedItem.Value , you will get the value stored in the named field you specified for "ValueProperty".

Assuming that you are certain that your query is returning rows, perhaps try adding the items "manually" rather than relying on automatic databinding.

private void GetOutlets()
{
    BOStockTransfer obj_StockTransfer = new BOStockTransfer();
    DataSet ds_OutletList = obj_StockTransfer.GetOutlets(connectionString);

    cmdoutletID.DisplayMember = "outletId";
    cmdoutletID.ValueMember = "pkID";
    cmdoutletID.BeginUpdate();
    try
    {
        cmdoutletID.Items.Clear();
        foreach (var row in ds_OutletList.Tables[0].Rows)
            cmdoutletID.Items(new { outletid = row["outletid"], pkID = row["primaryKeyIDFieldName"] });

    }
    finally { cmdoutletID.EndUpdate(); }
}

Answer 3

Try this:

BOStockTransfer obj_StockTransfer = new BOStockTransfer();
        DataSet ds_OutletList = obj_StockTransfer.GetOutlets(connectionString);

        if (ds_OutletList.Tables[0].Rows.Count != 0)
        {
            cmdoutletID.DataSource = ds_OutletList.Tables[0];
            cmdoutletID.DisplayMember = "outletname";
            cmdoutletID.ValueMember = "outletId";
        }

To capture selected value, for example on button click:

protected button1_Click(object o, EventArgs e)
{
  var selectedId =  cmboutletID.SelectedValue;
MessageBox.Show(selectedId);
}