Application User and still getting the logged in User Name

Hi

I have a very intranet situation where User opens the Web Page

Now here is calls a Database table where User Rights are stored

But access to this database table is given to dbo and Application Uer which is created in IIS Server folder by clicking on Allow Anomymous Login=true

when I try to run the Table Query and pass the USer Name I get null UserName

how to deal with this situation

 

Thanks

 

 

 
...