what is the daily minimum value of patient 1902's phosphate since 2104?
select min(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 1902 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'phosphate' ) and strftime('%y',labevents.charttime) >= '2104' group by strftime('%y-%m-%d',labevents.charttime)