when was the last time that patient 7112 during this hospital visit received a hemoglobin lab test?
select labevents.charttime from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'hemoglobin' ) and labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 7112 and admissions.dischtime is null ) order by labevents.charttime desc limit 1