2019-08-09：中位数计算

select "首剂抗生素中位数" as "指标名称", first_time as "数值" from 
(
    select  @ID:=@ID+1 AS ID, first_time from 
(
    select detail.uuid, TIMESTAMPDIFF(HOUR, csa.admission_date, if(antibiotic_execute_date is not null, antibiotic_execute_date, antibiotic_create_date)) as first_time  from cap_statistics_antibiotic as csa
    join yd_patient_11_basic_info as detail
    on detail.uuid=csa.uuid
--  where { discharge_date BETWEEN [ startTime2 ]} AND {[ endTime2 ]}
--  AND { inpatient_department = [ inpatient_department ]}  
--  AND { disease_name = [disease_class_name ]}  
--  AND { diagnosis_category = [ diagnose_class_name ]}
) as a, (SELECT @ID:=0) as b
order by first_time
) t where id = ((@ID+1) div 2)