try
            {

                //Object Of your Connection string (here named Connection).
                OleDbConnection con = new OleDbConnection(Connection);
                //Where Condition To Prevent Showing Empty Records In The your Field:
                OleDbDataAdapter da = new OleDbDataAdapter("Select YourField From YourTable Where YourField <>'')", con);
                DataSet ds = new DataSet();
                da.Fill(ds);
                con.Open();
                //Show Only Distinct Values (Do Not show repreated values) In the CboBx.
                cboBx1.DataSource = ds.Tables[0].DefaultView.ToTable(true,"YourField");
                cboBx1.ValueMember = "YourField";
                cboBx1.DisplayMember = "YourField";
                con.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

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