CREATE TABLE table_204_638 (id NUMBER, "year" NUMBER, "tournament" CLOB, "surface" CLOB, "round" CLOB, "winner" CLOB, "score" CLOB)

who won the most ?
SELECT "winner" FROM table_204_638 GROUP BY "winner" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "winner" FROM "table_204_638" GROUP BY "winner" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY