Which operating system has 1GB (mobile ddr) memory (RAM)?
CREATE TABLE "models" (
  "model" text,
  "memory_ram" text,
  "storage_flash" text,
  "operating_system_version" text,
  "memory_card" text,
  "weight_dimensions" text,
  "retail_availability" text
);
SELECT "operating_system_version" FROM "models" WHERE "memory_ram"='1gb (mobile ddr)';