1.registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
原因：Mybatis3.2 没有DAO接口，有DAO类和Mapper文件，DAO类需加@Repository注解
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException：Column 'release_time' in order clause is ambigous
原因：一般发生在多表连接查询，不知道列release_time是哪个表的列，ambigous：模棱两可