mysql join实例 mysql事件调度器

sELECT * FROM a LEFT JOIN b ON a.aID = b.bID;  a为主，a的数据全显示，连不上b的对应字段为空 

SELECT * FROM a RIGHT JOIN b ON a.aID = b.bID; b为主，b的数据全显示，连不上a的对应字段为空 
  
SELECT * FROM a INNER JOIN a ON a.aID = b.bID; 相当于where a.aID=b.bID

sHOW VARIABLES WHERE Variable_name = 'event_scheduler';  
 
#开启mysql事件调度器功能 
SET GLOBAL event_scheduler =1;