<?PHP

$mysqli = mysqli_init();
$mysqli->real_connect("localhost", "root", "", "corregidor");
$requete = "SELECT
  table_schema AS NomBaseDeDonnees, 
  ROUND(SUM( data_length + index_length ) / 1024 / 1024, 2) AS BaseDonneesMo 
FROM information_schema.TABLES
GROUP BY TABLE_SCHEMA;";
$resultat = $mysqli->query($requete);
while($obj = $resultat->fetch_object()){
	$nombase = $obj->NomBaseDeDonnees;
	$taille = $obj->BaseDonneesMo; 
	print "<br>Nom $nombase $taille";
}
?>

Oui c'est ce que je pensai aussi, mais là visiblement...
J'ai tester :

$G_bdd = new PDO('mysql:host='.$G_bdd_info['serveur'].';dbname='.$G_bdd_info['nom'].'', ''.$G_bdd_info['pseudo'].'', ''.$G_bdd_info['mdp'].'');

echo $G_bdd->query(" SELECT TABLE_NAME, CONCAT(ROUND(((DATA_LENGTH + INDEX_LENGTH - DATA_FREE) / 1024 / 1024), 2), 'Mo') AS TailleMo FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'base_v2' ");

Où base_v2 est le nom de ma base mais la valeur retournée est systématiquement 1. J'en ai tester d'autre mais même résultat...

$G_bdd = new PDO('mysql:host='.$G_bdd_info['serveur'].';dbname='.$G_bdd_info['nom'].'', ''.$G_bdd_info['pseudo'].'', ''.$G_bdd_info['mdp'].'');

echo $G_bdd->query(" SELECT TABLE_NAME, CONCAT(ROUND(((DATA_LENGTH + INDEX_LENGTH - DATA_FREE) / 1024 / 1024), 2), 'Mo') AS TailleMo FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'base_v2' ");