创建命名空间时一旦填写了已经存在的code，错误提示：
ERROR: DatalntegrityViolationException: could not execute statement; SQL in/al; constraint [uidx01 namespacel; nested exception is
org.hibernate.exception.ConstraintViolationException: could not execute statement

之后服务的其他模块也无法使用，错误提示：
ERROR：JpaSystemException: could not extract ResultSet; nested exception is org.hibernate.exception.GenericJDBCException: could not extract ResultSet