题解

SELECT 
	job_id,
	boss_id,
	company_id 
FROM
	( SELECT job_id, boss_id, company_id, job_city FROM job_info WHERE post_time > '2021-01-01 00:00:00' UNION SELECT job_id, boss_id, company_id, job_city FROM job_info WHERE job_city = '上海' ) a 
ORDER BY
	a.job_city