Official website of Sichuan University shows that the requirement for graduating from Sichuan University with a doctorate in computer science is to complete all credits within the prescribed time limit. The standard length of study for a doctor is three years, or two years for a master's or doctor's degree.
Doctor is a title for graduate students studying for a doctorate, and it can also be used to address people who have obtained a doctorate. In foreign countries, especially those who get a doctorate.