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

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