表删除时 Cannot delete or update a parent row: a foreign key constraint fails 异常处理
http://blog.sina.com.cn/s/blog_4cf2bac60100nylo.html
http://lgh-ken.iteye.com/blog/1149529
http://apps.hi.baidu.com/share/detail/2778123
http://www.iteye.com/problems/58307
http://topic.csdn.net/u/20120304/10/8bc0e16a-08cf-47a1-b8ce-de2aef563c6f.html
http://hi.baidu.com/latte88/blog/item/e1af974e6ce7ceced0c86ac6.html
