Drupal 7, query with WHERE and AND - drupal-7

Question

I would use this query :
SELECT g.id_site, g.commune, g.latitude, g.longitude, g.altitude, g.date, g.id_fiche, a.essence, e.nom_espece, e.effectif
FROM general g, arbre a, espece e
WHERE g.nom = a.nom AND g.id_fiche = e.id_fiche AND g.id_fiche = a.id_fiche
with the drupal 7 API. I try this :
$query = db_select('general' ,'g');
$query -> join ('arbre','a','a.nom = g.nom');
$query -> join ('espece','e','e.nom = a.nom');
$query -> fields ('g', array('commune','latitude','longitude','altitude','date','id_fiche'));
$query -> fields ('a', array('essence'));
$query -> condition ('g.id_fiche','e.id_fiche','=');
$query -> condition ('g.id_fiche','a.id_fiche','=');
But I get no result :/ the problem is these two lines :
$query -> condition ('g.id_fiche','e.id_fiche','=');
$query -> condition ('g.id_fiche','a.id_fiche','=');
If I comment this two lines, I have a result (but without the WHERE clause). What should I do for properly use the WHERE clause ?
thx =)

Answer 1

Ignoring the query issues and focusing on just the answer:
Try This:
I think you simply have to define all the fields you are actually going to use.
If that still does not work try use the Where Clause
$query = db_select('general' ,'g');
$query -> join ('arbre','a','a.nom = g.nom');
$query -> join ('espece','e','e.nom = a.nom');
$query -> fields ('e', array('id_fiche','nom'));
$query -> fields ('g', array('commune','latitude','longitude','altitude','date','id_fiche','nom'));
$query -> fields ('a', array('essence','nom'));
$query -> condition ('g.id_fiche','e.id_fiche','=');
$query -> condition ('g.id_fiche','a.id_fiche','=');

Answer 2

You can use db_query(), i found this method more usable.