CREATE TABLE table_203_501 (id NUMBER, "title" CLOB, "genre" CLOB, "sub\\u00addivisions" CLOB, "libretto" CLOB, "premiere date" CLOB, "place ,  theatre" CLOB)

which year did he release his last operetta ?
SELECT "premiere date" FROM table_203_501 ORDER BY id DESC LIMIT 1
SELECT "premiere date" FROM "table_203_501" ORDER BY "id" DESC FETCH FIRST 1 ROWS ONLY