What's the difference between these queries?

Question

Following how to select specific feid using a filter from access in C#

I have another question:

I recall this method whit a click event of SelectFeedbtn_Click and it works:

public static void GetSelectedFeed(Form2 frm2)
{
        string StrCon = System.Configuration.ConfigurationManager.ConnectionStrings["FeedLibraryConnectionString"].ConnectionString;

        OleDbConnection Connection = new OleDbConnection(StrCon);
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary", Connection);

        DataTable DTable = new DataTable();
        DataA.Fill(DTable);

        frm2.SelectedFeeddataGridView.DataSource = DTable;
}

but when I want to get an ID from FeedSelectListBox that DisplayMember is Feed Name / Description and ValueMember is ID it shows an exeption: {"Data type mismatch in criteria expression."} ,
the query is:

public static void GetSelectedFeed(Form2 frm2)
{
        string StrCon = System.Configuration.ConfigurationManager.ConnectionStrings["FeedLibraryConnectionString"].ConnectionString;

        OleDbConnection Connection = new OleDbConnection(StrCon);
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID = 'frm2.FeedSelectListBox.SelectedValue'", Connection);

        DataTable DTable = new DataTable();
        DataA.Fill(DTable);

        frm2.SelectedFeeddataGridView.DataSource = DTable;
}

What should I do ?

Answer 1

First thing, ID is an int so it should not be passed in quotes '' . You are passing frm2.FeedSelectListBox.SelectedValue as a string in query but you should pass its value with in the query so that it gets evaluated and your query becomes executable.

    OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID = "+frm2.FeedSelectListBox.SelectedValue, Connection);

    OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID = "+FeedSelectedID, Connection);