could somebody correct my following query, i am novice to software development realm, i am to a string builder object in comma separated form to my query but it's not producing desired result qyery is as follows and string cmd = "SELECT * FROM [placed_student] WHERE passout_year=@passout AND company_id=@companyId AND course_id=@courseId AND branch_id IN('" + sb + "')";

  StringBuilder sb = new
  StringBuilder();
              foreach (ListItem li in branch.Items)
              {

                  if (li.Selected == true)
                  {
                      sb.Append(Convert.ToInt32(li.Value)
  +", ");
                  }
              }
 li is integer value of my check box list which are getting generated may be differne at different time ...please also suggest me some good source to learn sql..