成功的拆开了SELECT里JOIN个SELECT是啥

SELECT *       
  FROM table JOIN table ON a=b
-----------------------
  JOIN (SELECT*
          FROM table
           JOIN table
            ON c=d
            WHERE time BETWEEN DATE '*' AND DATE  '*') COM1 ON e = f
  ----------------------
 WHERE x = 14
   AND y = 'a'
  

终于搞明白这个COM1是哪来的了