CREATE TABLE table_204_778 (id DECIMAL, "code" DECIMAL, "county" TEXT, "former province" TEXT, "area  ( km2 ) " DECIMAL, "population\ census 2009" DECIMAL, "capital" TEXT)

did mombasa or tana river have a larger population in 2009 ?
SELECT "county" FROM table_204_778 WHERE "county" IN ('mombasa', 'tana river') ORDER BY "population\ncensus 2009" DESC LIMIT 1
SELECT "county" FROM "table_204_778" WHERE "county" IN ('mombasa', 'tana river') ORDER BY "population\ncensus 2009" DESC NULLS LAST LIMIT 1