将参数传递到where子句并刷新网格视图-C＃

Question

I would like to filter a datagridview by selecting a value in a combobox.

The top part of my code is a form that inserts data into a table on our server based on a customer profile which is pulled from a view but when a user selects the customer in the top combobox I would like the datagridview to show previous transactions from the table.

The code below contains comments of where I will insert the actual code, but wanted to know if I am on the right track.

 private void combobox_SelectedChangeCommitted(object sender, EventArgs e)
 {
   // CONNECTION STRING
  {
            connection.Open();

   //change value into a parameter ready for the next step

   //run SQL Command (select * from xxxx where column = @parameter)

   //FILL DATA GRID

            connection.Close();
   }
  }

Regards,

Neil

Answer 1

You should bind your Combobox SelectedItem property to your ViewModel like so:

SelectedItem="{Binding UserSelection, Mode=TwoWay}"

And then in your ViewModel your property would be something like so:

private string _userSelection;
public string UserSelection
{
    get
    {
        return _userSelection;
    }
    set
    {
        _userSelection = value;
        UpdateData();
        OnPropertyChanged();
    }
}

Then you'd implement your database code something like this:

private void UpdateData(){
    Task.Factory.StartNew(()=>{
        connection.Open();
        DataProperty = yourNewData;
        connection.Close();
    });
}

That way you're not doing any database reading/updating on the UI thread, locking your application.

Of course, in a decently written WPF application you'd bind your DataGrid to the DataProperty that I showed in the example code.