fix: use count to instead of result[0]['COUNT(0)']

Author: XadillaX

lib/query.js

@@ -719,8 +719,8 @@ Query.prototype.count = function(callback) {
             count = parseInt(result[0]["COUNT(0)"]) || 0;
         }
 
-        callback(undefined, result[0]["COUNT(0)"]);
-        promisor._onExecuteResult(undefined, result[0]["COUNT(0)"]);
+        callback(undefined, count);
+        promisor._onExecuteResult(undefined, count);
     });
 
     return promisor;