Yes Enum is Better.....approach....as Ramy says...

By using this query u'll get one Result.......from that u can check......userType

string st=Data["UserType"].ToString();
if(st=="Admin")
{//Open Admin Form}
else if(st=="User")
{// Open User...

Okay i thought.....he/she uses the single table....actually he/she writes...."The user login details for both admin and normal users are in a single table called account.."
if the user Type (admin...

Well Dear ....... u r saying u r developing a Windows Application ........There is nothing like Session in Windows app.....Session are used in Web app.
is there any Flag....in ur user table.....???...