如何使用过滤器从 C# 中的访问中选择特定字段

Question

in C# and windows Form,

I have a database like this:

and this is how I using a class put it's data into a datagridview :

    class DBConnection
{
    public static void GetList(Form2 frm2)
    {
        string DBPath = Application.StartupPath;
        OleDbConnection Connection = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+DBPath+@"\DataBase\SampleFeeds.accdb");
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary", Connection);
        DataTable Dtable = new DataTable();
        DataA.Fill(Dtable);
        frm2.SelectedFeeddataGridView.DataSource = Dtable;
    }

}

and this is my form load:

private void Form2_Load(object sender, EventArgs e)
    {
        DBConnection.GetList(this);
    }

So far everything is ok.

now I have a question:

for example I have a list box FeedSelectListBox , I want to when user click on a button GrassLegumeForagebtn my FeedSelectListBox fill with only all of Feed Names that are in the category of Grass / Legume Forage.

how should I do that ?

with help of Damirchi My problem solved

//-----------------

But now I have another question: I want to when user select a feed from list box all of it's data from data base (like name, number, feed type and ,,,) put in a data grid view.

I used this code on my SelectFeedbtn but it doesn't work :

private void SelectFeedbtn_Click(object sender, EventArgs e)
    {
        string StrCon = System.Configuration.ConfigurationManager.ConnectionStrings["FeedLibraryConnectionString"].ConnectionString;
        OleDbConnection Connection = new OleDbConnection(StrCon);
        string FeedSelectedID = FeedSelectListBox.SelectedValue.ToString();
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID = 'FeedSelectedID'" , Connection);
        DataTable DTable = new DataTable();
        DataA.Fill(DTable);
        SelectedFeeddataGridView.DataSource = DTable;
    }

And ValueMember property of FeedSelectListBox is ID but the error is :

An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll.

I even use this query but it still doesn't work:

OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID =" FeedSelectListBox.SelectedValue , Connection);

Answer 1

at first you most set the DisplayMember and ValueMember properties of FeedSelectListBox and use this code on click event. you can put this code on GrassLegumeForagebtn click event.

string DBPath = Application.StartupPath;
        OleDbConnection Connection = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+DBPath+@"\DataBase\SampleFeeds.accdb");
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where category='Grass / Legume'", Connection);
        DataTable Dtable = new DataTable();
        DataA.Fill(Dtable);
        frm2.FeedSelectListBox .DataSource = Dtable;