请教选择查询的问题
如图所示，已可实现时间段的选择查询问题。但是勾选其他选项后，实现的是全部数据的查询，无法实现某一时间段特定选项的查询。代码如下，本人小白，还请各位大侠不吝赐教。

private void btnSelect_Click(object sender, EventArgs e)
        {

            DataSet ds = new DataSet();
            ds.Clear();
         
            string queryselect = "select * from jt where 1=1 ";

            if (cb1.Checked)
            {
                queryselect += " and model = '" + cbbcategory.Text + " '";
            }
            if (cb2.Checked)
            {
                queryselect += " and modelnumber" + " like '%" + txtMN.Text + "%'";
            }
            if (cb3.Checked)
            {
                queryselect += " and problemdescribe" + " like '%" + cbbQC.Text + "%'";
            }
            if (cb4.Checked)
            {
                queryselect += " and author" + " like '%" + txtAuthor.Text + "%'";
            }
            if (cb7.Checked)
            {
                queryselect += " and data" + " like '%" + txtData.Text + "%'"; 
 
            }
            
            if (cb5.Checked && cb6.Checked)
            {
               string ss = dateTimePicker1.Value.Date.ToString("yyyy-MM-dd 23:00:00");
               string ee = dateTimePicker2.Value.Date.ToString("yyyy-MM-dd 23:00:00");
               queryselect = "select * from jt where data between #" + ss + "# and #" + ee + "# ";
            }

[解决办法]
上面的错了，应该是：

            if (cb5.Checked && cb6.Checked)
            {
               string ss = dateTimePicker1.Value.Date.ToString("yyyy-MM-dd 23:00:00");
               string ee = dateTimePicker2.Value.Date.ToString("yyyy-MM-dd 23:00:00");
               queryselect = "select * from jt where data between #" + ss + "# and #" + ee + "# ";
            }

改成

            if (cb5.Checked && cb6.Checked)
            {
               string ss = dateTimePicker1.Value.Date.ToString("yyyy-MM-dd 23:00:00"); 
 
               string ee = dateTimePicker2.Value.Date.ToString("yyyy-MM-dd 23:00:00");
               queryselect += " and data between #" + ss + "# and #" + ee + "# ";
            }