instruction: how much patient 32755's ph changes/differs second measured on the first hospital visit compared to the first value measured on the first hospital visit?
response: SELECT (SELECT labevents.valuenum FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 32755 AND NOT admissions.dischtime IS NULL ORDER BY admissions.admittime LIMIT 1) AND labevents.itemid IN (SELECT d_labitems.itemid FROM d_labitems WHERE d_labitems.label = 'ph') ORDER BY labevents.charttime LIMIT 1 OFFSET 1) - (SELECT labevents.valuenum FROM labevents WHERE labevents.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 32755 AND NOT admissions.dischtime IS NULL ORDER BY admissions.admittime LIMIT 1) AND labevents.itemid IN (SELECT d_labitems.itemid FROM d_labitems WHERE d_labitems.label = 'ph') ORDER BY labevents.charttime LIMIT 1)