今天在写多个删除功能的时候出现了这么一个错误：意思是删除操作的时候，没有找到对应的外键。
Cannot delete or update a parent row: a foreign key constraint fails (`ssh03`.`role_privilege`, CONSTRAINT `FK45FBD628F05C38CB` FOREIGN KEY (`role_id`) REFERENCES `role` (`roleId`))
Cannot delete or update a parent row: a foreign key constraint fails (`ssh03`.`role_privilege`, CONSTRAINT `FK45FBD628F05C38CB` FOREIGN KEY (`role_id`) REFERENCES `role` (`roleId`))
Could not execute JDBC batch update
Could not execute JDBC batch update; SQL [delete from role where roleId=?]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
org.springframework.dao.DataIntegrityViolationException: Could not execute JDBC batch update; SQL [delete from role where roleId=?]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update在网上找了很久，都没有找到对应的错误。。我的删除操作是先查找Role对象，再通过删除它。
后来debug起来又是匪夷所思的：后台能够得到外界传递过来的id
![Could not execute JDBC batch update; SQL [delete from role where roleId=?]; constraint [null]; neste_javascript](https://s2.51cto.com/images/blog/202107/07/f8ab9751bf1bae1ea2f5ceafa2ec78f1.png?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_30,g_se,x_10,y_10,shadow_20,type_ZmFuZ3poZW5naGVpdGk=/resize,m_fixed,w_1184)
在查询对象的时候，就死活查不了外键的数据【让我搞了很久很久】。。
![Could not execute JDBC batch update; SQL [delete from role where roleId=?]; constraint [null]; neste_javascript_02](https://s2.51cto.com/images/blog/202107/07/941f1e205ef929f63ec1e0c07d3c8cab.png?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_30,g_se,x_10,y_10,shadow_20,type_ZmFuZ3poZW5naGVpdGk=/resize,m_fixed,w_1184)
最后发现id上多了一个空格？？？？？？？至于为什么多了一个空格，，我现在还不知道。。。于是把空格去掉，就解决这个bug了。。。
/*批量删除*/
public String deleteSelect() {
for (String s : selectedRow) {
roleServiceImpl.delete(s.trim());
}
return "list";
}
….如果知道为什么会多出一个空格的，请在评论下告诉我….
