This function allows you to get DNN profile properties from the system.

You can even ask for custom properties you added yourself.

CREATE FUNCTION [dbo].[BIT_GetPropertyValue] 
(
    @PortalID int, -- portalid
    @UserID   int, -- UserID
    @Property nvarchar(100) -- name of the property to read
)
RETURNS   nVarChar(4000)  -- the value of the property for the user
AS
BEGIN
DECLARE @RetVal AS nVarChar(4000) = ''
select @RetVal = PropertyValue
from UserProfile
where UserID = @UserID
and PropertyDefinitionID = dbo.GetProfilePropertyDefinitionID (@PortalID,@Property)

RETURN @RetVal
END