CREATE TABLE table_203_731 (id DECIMAL, "pos." TEXT, "city" TEXT, "population\ ( ab ) " DECIMAL, "surface\ ( km2 ) " DECIMAL, "density\ ( ab/km2 ) " DECIMAL, "altitude\ ( mslm ) " DECIMAL)

what is the density of the last city ?
SELECT "density\n(ab/km2)" FROM table_203_731 ORDER BY "pos." DESC LIMIT 1
SELECT "density\n(ab/km2)" FROM "table_203_731" ORDER BY "pos." DESC NULLS LAST LIMIT 1