1. Non-fresh graduates who are studying in universities are not allowed to take the civil service examination. Because you haven't obtained the corresponding diploma and degree certificate. It is clearly mentioned in the announcement of civil service recruitment.
2. fresh graduates who are studying can apply for the exam. For example, if you are a senior now, you can apply for the national civil service examination and provincial civil service recruitment, but you need to ensure that you get the corresponding diploma and degree certificate before you can go to work. So you can go to work directly after graduation.