select  * from t_project_usage order by end_time desc  limit 50

select  project_id,max(server_count) server_count,
	max(cpu_count) cpu_count, sum(cpu_hours) cpu_hours,
	max(memory_size) memory_size, sum(memory_hours) memory_hours,
	max(volume_size) volume_size, sum(volume_hours) volume_hours   
from t_project_usage 
where start_time>='2017-01-01' and end_time<'2017-03-02'
group by project_id