Case 1: Intra scope, intra city transfer
You are still with working with your current employer, found the same position in the same city with approbation of both employers.
Case 2: Extra city transfer
Relocation to another city, with cooperative employers and same work position
Case 3: Extra scope/industry transfer
Changing job for another industry or another position, with cooperative employers in the same city
Case 4: Resident permit & work permit cancelled
Your work permit is cancelled as is your resident permit, but your employer gave you the release letter and cancellation letter.
Case 5: Reluctant employers
Your employers won’t give your cancellation letter and/or release letter.
5. Tianjin administrations address book (direct link)