查询以获取表中有记录的ID列表

public IQueryable <fruits> GetAllfruitsIDs() {
      return fruits.AsQueryable();
    }

    var data = GetAllfruitsIDs();

   // Or u can use this :
     public IEnumerable<fruits> GetAllfruitsIDs() {
              return fruits.AsQueryable().ToList;
            }

        var data = GetAllfruitsIDs();

var result = fruits.Where(f => fruitIds.Contains(f.FruitId));

List<string> fruitIdsThatExistInDyanmoDb = fruits.Where(f => fruitIds.Contains(f.FruitId))
             .Select(f=> f.FruitId).ToList();