MySQL not recognizing virtual column / field - mysql

Question

I'm trying to manipulate two virtual fields generated of a subquery into a new field, but MySQL is telling me that "GP" is an unknown column, but it has been already declared. Please, take a look at my query:
SELECT *,
(SELECT COUNT(id_gol) FROM tb_gol as gol
INNER JOIN tb_jogo as jg ON(gol.fk_id_jogo = jg.id_jogo)
WHERE gol.ic_excluido != '*' AND gol.fk_id_equipe = e.id_equipe AND jg.fk_id_campeonato = g.fk_id_campeonato) as 'GP',
(SELECT COUNT(id_gol) FROM tb_gol as gol
INNER JOIN tb_jogo as jg ON(gol.fk_id_jogo = jg.id_jogo)
WHERE gol.ic_excluido != '*' AND gol.fk_id_equipe != e.id_equipe AND (jg.fk_id_equipe1 = e.id_equipe OR jg.fk_id_equipe2 = e.id_equipe) AND jg.fk_id_campeonato = g.fk_id_campeonato) as 'GC',
(SELECT COUNT(id_wo) as WOs FROM tb_wo as w INNER JOIN tb_jogo as j ON (w.fk_id_jogo = j.id_jogo) WHERE w.fk_id_equipe = e.id_equipe AND j.fk_id_campeonato = g.fk_id_campeonato) as 'WO',
(GP+(GC*-1)) as 'SALDO'
FROM tb_equipe as e
INNER JOIN tb_gruposEquipes as ge ON (e.id_equipe = ge.fk_id_equipe)
INNER JOIN tb_grupos as g ON (g.id_grupo = ge.fk_id_grupo)
WHERE g.fk_id_campeonato = 23
ORDER BY WO ASC
As you can see, "SALDO" would be the result of "GP-GC". But MySQL do not recognize these columns
How can I solve this?
SOLUTION
Thanks a lot for the help, guys, but I figured out the problem.
"SALDO" couldn't be created by substracting GC of GP because "GP" and "GC" doesn't exist during runtime.
So, when you need to manipulate virtual fields during the runtime, you'll have to repeat the code that generated the virtual field.
Then, if you have this select:
SELECT *, (field1+1) as 'GP', (field2+1) as 'GC', (GP+GC) as 'SALDO' FROM (...)
You'll need to replace it with this:
SELECT *, (field1+1) as 'GP', (field2+1) as 'GC', ((field1+1)+(field2+1)) as 'SALDO' FROM (...)

Answer 1

Push the stuff into in inner query
SELECT core.*,
(GP+(GC*-1)) as 'SALDO'
from (
(SELECT COUNT(id_gol) FROM tb_gol as gol
INNER JOIN tb_jogo as jg ON(gol.fk_id_jogo = jg.id_jogo)
WHERE gol.ic_excluido != '*' AND gol.fk_id_equipe = e.id_equipe AND jg.fk_id_campeonato = g.fk_id_campeonato) as 'GP',
(SELECT COUNT(id_gol) FROM tb_gol as gol
INNER JOIN tb_jogo as jg ON(gol.fk_id_jogo = jg.id_jogo)
WHERE gol.ic_excluido != '*' AND gol.fk_id_equipe != e.id_equipe AND (jg.fk_id_equipe1 = e.id_equipe OR jg.fk_id_equipe2 = e.id_equipe) AND jg.fk_id_campeonato = g.fk_id_campeonato) as 'GC',
(SELECT COUNT(id_wo) as WOs FROM tb_wo as w INNER JOIN tb_jogo as j ON (w.fk_id_jogo = j.id_jogo) WHERE w.fk_id_equipe = e.id_equipe AND j.fk_id_campeonato = g.fk_id_campeonato) as 'WO' )
FROM tb_equipe as e
) as core
INNER JOIN tb_gruposEquipes as ge ON (core.id_equipe = ge.fk_id_equipe)
INNER JOIN tb_grupos as g ON (g.id_grupo = ge.fk_id_grupo)
WHERE g.fk_id_campeonato = 23
ORDER BY WO ASC