使用LINQ和Entity框架检查c#var中的空值

var query = from item in context.Items
            where item.Property != null
            select item;

var firstNonNullItem = (from item in context.Items
                        where item.Property != null
                        select item).FirstOrDefault();

bool hasNonNullItems = (from item in context.Items
                        where item.Property != null
                        select item).Any();

int nonNullItemCount = (from item in context.Items
                        where item.Property != null
                        select item).Count();

var singleNonNullItem = (from item in context.Items
                         where item.Property != null
                         select item).SingleOrDefault();

var distinctNonNullItems = (from item in context.Items
                            where item.Property != null
                            select item).Distinct();

var sortedNonNullItems = (from item in context.Items
                          where item.Property != null
                          orderby item.Property
                          select item);

var pagedNonNullItems = (from item in context.Items
                         where item.Property != null
                         orderby item.Property
                         select item).Skip(10).Take(20);

var groupedNonNullItems = from item in context.Items
                          where item.Property != null
                          group item by item.Property into itemGroup
                          select new { Key = itemGroup.Key, Items = itemGroup };

var joinedNonNullItems = from item in context.Items
                         join otherItem in context.OtherItems on item.Property equals otherItem.Property
                         where item.Property != null
                         select new { Item = item, OtherItem = otherItem };