CREATE TABLE table_204_520 (id NUMBER, "outcome" CLOB, "no." NUMBER, "date" NUMBER, "championship" CLOB, "surface" CLOB, "opponent" CLOB, "score" CLOB)

what is the only indoor championship ?
SELECT "championship" FROM table_204_520 WHERE "surface" = 'indoor'
SELECT "championship" FROM "table_204_520" WHERE "surface" = 'indoor'