mysql & php: temporary/ virtual ids for query results?

I wonder if it is possible to assign temporary/ virtual IDs for a query result?

For ins开发者_Go百科tance, I have this as my query,

SELECT 

pg_id AS ID,
pg_url AS URL,
pg_title AS Title,
pg_content_1 AS Content

FROM root_pages

ORDER BY pg_created DESC

output:

ID  URL     Title   Content 
53  a       A       xxx 
40  b       B       xxx 
35  c       C       xxx  

you can see the the gap between the IDs - they are very untidy. I wonder if I can make a virtual column or something so that I have the output below,

ID  URL     Title   Content  Virtual ID
53  a       A       xxx      3
40  b       B       xxx      2
35  c       C       xxx      1 

from a query like this below,

SELECT 

pg_id AS ID,
pg_url AS URL,
pg_title AS Title,
pg_content_1 AS Content

FROM root_pages

ORDER BY virtual_id DESC 

is it possible??

thanks!

If you still persist on getting the position of each row take a look at this answer

MySQL get row position in ORDER BY