* .AsEnumerable()延迟执行,不会立即执行。当调用.AsEnumerable()的时候,实际上什么都没有发生。
* .ToList()则是立即去执行
* 下面的两个实体类的多条件查询就是运用了先AsEnumerable,再ToList,这样可以直接执行一次,不然就去执行多次ToList using
(var db = new DB()) { var list =db.OrderMains.AsEnumerable(); var list2 =
db.Markets.AsEnumerable(); //如果查询条件中的某一个不为空的时候,则用下面的多条件查询语句 if
(condition.order_Id.IsNotNullOrEmpty()) { list = list.Where(t1 =>
t1.order_Id.Contains(condition.order_Id)); } if
(condition.orderDate.IsNotNullOrEmpty()) { list = list.Where(t1 =>
Convert.ToDateTime(t1.orderDate)>= Convert.ToDateTime(condition.orderDate)); }
if (condition.marketId.IsNotNullOrEmpty()) { list2 = list2.Where(t2 =>
t2.Name.Contains(condition.marketId)); } if
(condition.orderMoney.IsNotNullOrEmpty()) { list = list.Where(t1 =>
Convert.ToDateTime(t1.orderDate) <= Convert.ToDateTime(condition.orderMoney));
} var result = (from t1 in list join t2 in list2 on t1.marketId equals
t2.Market_Id select new { Id = t1.Id, orderDate = t1.orderDate, orderMoney =
t1.orderMoney, marketId = t2.Name, order_Id = t1.order_Id }).ToList(); return
result; }
转载请注明出处:https://mp.csdn.net/postedit/82746018
<https://mp.csdn.net/postedit/82746018>

友情链接
ioDraw流程图
API参考文档
OK工具箱
云服务器优惠
阿里云优惠券
腾讯云优惠券
华为云优惠券
站点信息
问题反馈
邮箱:ixiaoyang8@qq.com
QQ群:637538335
关注微信