How to transfer Sichuan social security to Chengdu social security

The difference between Sichuan social security and Chengdu social security lies in:

1. According to the regulations of Chengdu social security, farmers (whether local or foreign) can only participate in comprehensive insurance. Those who have participated in social security before can continue to participate in social security if they want. In other words, if the unit can also transfer to comprehensive insurance, urban hukou (whether local or foreign) must participate in social security?

2. The payment base of comprehensive insurance is 60%, 80% and 100% of Chengdu's social wage. According to the salary of employees, which base is closest, the payment ratio is 14.5%, and the individual is 5.5%.