using user.identity.name

Hi at all :D
        Dim cmdstring As String = "Select Code from example" '&  devo metterci il nome dell utente
Dim cmdstring As String = "Select Code from example" ' &  user name
i must insert in the master page vb the code "" user.identity.name"" but the controlo command haven't 
that voice.... :'( 
plzzzz helpppppp meeeeeeee




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