Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Doha to Nanjing as you normally would.
DOH stands for Doha Hamad Intl Airport, while NKG stands for Nanjing Lukou Intl Airport. These codes are often called IATA codes, a set of identifiers established by IATA (International Air Transport Association) that is widely used by airlines and the aviation industry.