CREATE TABLE table_name_68 (population NUMBER, simplified VARCHAR2, area VARCHAR2)

What's the sum of the population for the place simplified with an area smaller than 2,879?
SELECT SUM(population) FROM table_name_68 WHERE simplified = "上杭县" AND area < 2 OFFSET 879
SELECT SUM("population") FROM "table_name_68" WHERE "area" < 2 AND "simplified" = "上杭县" OFFSET 879 ROWS