Linq to SQL-分组依据和计数

只需使用以下

Count

from buildinguser in db.GetTable<BuildingUser>()join building in db.GetTable<Building>()on buildinguser.ID_BUILDING equals building.IDjoin user in db.GetTable<User>()on buildinguser.ID_USER equals user.IDgroup building by building.NAME into grpBuildingselect new{    building = grpBuilding.Key,    users = grpBuilding.Count()};