winform combobox 实现模糊查询

        private void BindPaperCodeA()
        {
            //绑定数据时 删除 SelectedIndexChanged 
            cmbPaperCode.SelectedIndexChanged -= new EventHandler(cmbPaperCode_SelectedIndexChanged);

            cmbPaperCode.ValueMember = "id"; cmbPaperCode.DisplayMember = "call";
            DataTable dt = pagerModelBLL.GetList(" state=" + ((int)EState.Normal).ToString() + " and  paper_code=" + cmbPaperType.SelectedValue.ToString()).Tables[0];
            DataRow dr = dt.NewRow();
            dr["id"] = "0";
            dr["call"] = "全部";
            dt.Rows.InsertAt(dr, 0);
            cmbPaperCode.DataSource = dt;

            //绑定数据完成时 绑定SelectedIndexChanged事件
            cmbPaperCode.SelectedIndexChanged += new EventHandler(cmbPaperCode_SelectedIndexChanged);
        }

private void cmbPaperCode_TextUpdate(object sender, EventArgs e)
        {
            cmbPaperCode.ValueMember = "id"; cmbPaperCode.DisplayMember = "call";
            DataTable dt = pagerModelBLL.GetList(" state=" + ((int)EState.Normal).ToString() + " and  paper_code=" + cmbPaperType.SelectedValue.ToString()).Tables[0];
            DataRow dr = dt.NewRow();dr["id"] = "0";dr["call"] = "全部";dt.Rows.InsertAt(dr, 0);
            if (string.IsNullOrEmpty(cmbPaperCode.Text.Trim()))
            {
                cmbPaperCode.DataSource = dt;
            }
            else
            {
                DataTable dt2 = pagerModelBLL.GetList(" state=" + ((int)EState.Normal).ToString() + " and call like ‘" + cmbPaperCode.Text.Trim() + "%‘ and  paper_code=" + cmbPaperType.SelectedValue.ToString()).Tables[0];
                if (dt2 != null && dt2.Rows.Count > 0)
                {
                    DataRow[] drS = dt2.Select(" call= ‘" + cmbPaperCode.Text + "‘");
                    if (drS.Length > 0)
                    {
                        cmbPaperCode.DataSource = dt2;
                        cmbPaperCode.SelectedValue = drS[0]["id"].ToString();
                    }
                    else
                    {
                        DataRow dr2 = dt2.NewRow();
                        dr2["id"] = "0";
                        dr2["call"] = cmbPaperCode.Text;
                        dt2.Rows.InsertAt(dr2, 0);
                        cmbPaperCode.DataSource = dt2;

                        //保持鼠标指针原来状态，有时候鼠标指针会被下拉框覆盖，所以要进行一次设置。
                        Cursor = Cursors.Default;
                        //自动弹出下拉框
                        cmbPaperCode.DroppedDown = true;
                        cmbPaperCode.SelectionLength = 0;
                        //设置光标位置，否则光标位置始终保持在第一列，造成输入关键词的倒序排列
                        cmbPaperCode.SelectionStart = cmbPaperCode.Text.Length;
                    }
                }
                else
                {
                    cmbPaperCode.DataSource = dt;
                }
            }
        }