connecing SQL server database and retrieving data using C#, (i am editin)

namespace employee_info
{
public partial class _Default : System.Web.UI.Page
{
protected string SHQAPRDConn = System.Configuration.ConfigurationManager.AppSettings["SHQAPRDConn"];
 
protected void Page_Load(object sender, EventArgs e)
{
string login_user;
login_user = User.Identity.Name;
int int_substring = login_user.IndexOf("\\");
login_user = login_user.Substring(int_substring + 1);
login_user = "";
lblMsg.Text = login_user;
 
{
string strSql;
SqlConnection con = new SqlConnection(Conn);

SqlCommand objCmd;
SqlDataAdapter daEmployee;
SqlDataAdapter daVisa;
DataTable dtEmployee = new DataTable();
DataTable dtVisa = new DataTable();
strSql = "SELECT A.EMPLID, A.FIRST_NAME, A.LAST_NAME";
strSql = strSql + " FROM PS_EMPLOYEES A where EMPLID = '" + login_user + "'";

con.Open();
objCmd = new SqlCommand(strSql, con);
objCmd.CommandType = CommandType.Text;
daEmployee = new SqlDataAdapter(objCmd);
daEmployee.Fill(dtEmployee);
 
foreach (DataRow myRow in dtEmployee.Rows)
{
txtFirstName.Text = myRow[1].ToString().Trim();
txtLastName.Text = myRow[2].ToString().Trim();

}
 
 
 
strSql = "SELECT max(EFFDT) , max(EXPIRATN_DT)";
strSql = strSql + " FROM PS_VISA_PMT_DATA where EMPLID = '" + login_user + "'";
con.Close();
objCmd.Dispose();
con = new SqlConnection(SHQAPRDConn);
con.Open();
objCmd = new SqlCommand(strSql, con);
objCmd.CommandType = CommandType.Text;
daVisa = new SqlDataAdapter(objCmd);
daVisa.Fill(dtVisa);

foreach (DataRow myRow in dtVisa.Rows)
{
txtEffdt.Text = DateTime.Parse(myRow[0].ToString()).ToString("dd/MMM/yyyy");
txtExp.Text = DateTime.Parse(myRow[1].ToString()).ToString("dd/MMM/yyyy");
}
 
 
 
objCmd.Dispose();
daEmployee.Dispose();
daVisa.Dispose();
dtEmployee.Dispose();
dtVisa.Dispose();
con.Close();