CREATE TABLE table_201_21 (id NUMBER, "year" NUMBER, "title" CLOB, "role" CLOB, "notes" CLOB)

which role is the most common from all the titles ?
SELECT "role" FROM table_201_21 GROUP BY "role" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "role" FROM "table_201_21" GROUP BY "role" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY