CREATE TABLE table_204_579 (id DECIMAL, "code" TEXT, "district" TEXT, "headquarters" TEXT, "population  ( as of 2011 ) " DECIMAL, "area  ( km2 ) " DECIMAL, "density  ( /km2 ) " DECIMAL)

which has a larger population , dehradun or nainital ?
SELECT "district" FROM table_204_579 WHERE "district" IN ('dehradun', 'nainital') ORDER BY "population (as of 2011)" DESC LIMIT 1
SELECT "district" FROM "table_204_579" WHERE "district" IN ('dehradun', 'nainital') ORDER BY "population (as of 2011)" DESC NULLS LAST LIMIT 1