CREATE TABLE table_1828368_1 (pop_density__km_2__ VARCHAR2, area__km_2__ VARCHAR2)

What are the population densities of all communes with an are of 28.3 sq.km.?
SELECT pop_density__km_2__ FROM table_1828368_1 WHERE area__km_2__ = "28.3"
SELECT "pop_density__km_2__" FROM "table_1828368_1" WHERE "28.3" = "area__km_2__"