What is the full official name of the current legislator that has served for the most number of terms?
served for the most number of terms refers to MAX(COUNT(bioguide));
SELECT T1.official_full_name FROM current AS T1 INNER JOIN `current-terms` AS T2 ON T1.bioguide_id = T2.bioguide GROUP BY T1.official_full_name, T2.bioguide ORDER BY COUNT(T2.bioguide) DESC LIMIT 1