Subquery referencing DB name in FROM

[David Lage]

SELECT DISTINCT table1.`table`
FROM (

SELECT concat( 'db_', vsc.stat_db_id, '.music_song_play_day_summary' ) AS `table`
FROM db.stat_controller AS vsc
WHERE vsc.table_prefix = 'music_song_play'
AND vsc.type = 'active'
) AS table1

Basicly this returns

table
'db_1.music_song_play_day_summary'

SELECT table2. *
FROM (

SELECT DISTINCT table1.`table`
FROM (

SELECT concat( 'db_', vsc.stat_db_id, '.music_song_play_day_summary' ) AS `table`
FROM db.stat_controller AS vsc
WHERE vsc.table_prefix = 'music_song_play'
AND vsc.type = 'active'
) AS table1
) AS table2

And this returns the same thing

table
'db_1.music_song_play_day_summary'

And keeps doing it for as long as i keep subquering. Is this a bug?

I have db's like the following...

db

db_1
db_2
db_3