Expression<Func<CustomerType, bool>> expression = c => (c.Id != null);
var c = from u in ccc
where u.Name == editModel.Name
select u.Name;
ccc.Select(u => u.Name == "");
ccc.Where(u => u.Name == "").Any(u=>u.Name=="");
1，var cumtomerType = dbContext.CustomerTypes.FirstOrDefault(me => me.Id == id);
2，list = dbContext.CustomerTypes.Where(expression).OrderByDescending(c => c.CreateTime).Skip((pageIndex - 1) * pageSize).Take
3，query.Any(,)确定序列是否包含
select挑选列，where用于筛选