SQL Server :: Checkboxlist Listitem Checked According To DB?

i want to show checkboxlist listitem checked according to option value saved in DB like this:

,2,
2
1,,3
1,2,3

//accessing value
protected void getreportType()
{
SqlCommand cmd = new SqlCommand("SELECT * from reporttype", con);
con.Open();
CheckBoxList1.DataSource = cmd.ExecuteReader();
CheckBoxList1.DataBind();
con.Close();
//getting previous checked items
SqlCommand cmdx = new SqlCommand("SELECT report_type from projects where serial_no='" + Convert.ToInt32(Request.QueryString["id"].ToString()) + "'", con);......

but it is only shows checked item of column which have single value without comma means like "2" otherwise not shows any selected listitem from any colums