what is patient 94293's daily average level of asparate aminotransferase (ast) during their first hospital encounter?
select avg(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 94293 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'asparate aminotransferase (ast)' ) group by strftime('%y-%m-%d',labevents.charttime)