SELECT  
      COUNT (( Appels.id)) AS test1
FROM descro  
     INNER JOIN Appels ON (descro.id = Appels.id)  
     AND (descro.id = Appels.id);

SELECT  
      COUNT (DISTINCT ( Appels.id)) AS test1
FROM descro  
     INNER JOIN Appels ON (descro.id = Appels.id) AND (descro.id = Appels.id);