var querdataset = from item in dt.AsEnumerable()
group item["logip"] by //分组
item["logip"] into newGroup//分组key放到 newGroup 中
orderby newGroup.Count() descending //排序
select newGroup;
group item["logip"] by //分组
item["logip"] into newGroup//分组key放到 newGroup 中
orderby newGroup.Count() descending //排序
select newGroup;