标签：highlight lambda表达式 == border 使用 完整 count ice mod
在网上有很多人都在查找Lambda的例子，但是完整的例子不多，况且还有相当一部分几乎完全不能用，LINQ的左连倒是挺多的，但是LINQ的代码相对比较少，一旦遇到重复数据的时候，不容易被过滤，Lambda就可以轻松避免这个让人头疼的问题。废话不多说，看下面的例子吧。
var model_main = from o in db.Main where o.OrderIsdel == 0 select o;
var model_user = from u in db.User select u;
var model_device = from d in db.Device select d;
var model_team = from t in db.Team select t;
var sub_model = from sub in db.SubOrder select sub;
var model_order_user = model_order.GroupJoin(model_user, o => o.OrderUserId, u => u.UserId, (o, u) => new { o, u }).SelectMany(p => p.u.DefaultIfEmpty(), (p, u) => new OrderModel()
{
OrderDeviceId = p.o.OrderDeviceId,
OrderId = p.o.OrderId,
OrderUserId = p.o.OrderUserId,
OrderTeamID = p.o.OrderTeamID,
OrderUserNickName = u.UserName,
});
var model_order_user_device = model_order_user.GroupJoin(model_device, o => o.OrderDeviceId, d => d.DeviceId, (o, d) => new { o, d }).SelectMany(p => p.d.DefaultIfEmpty(), (p, d) => new OrderModel()
{
OrderDeviceId = p.o.OrderDeviceId,
OrderId = p.o.OrderId,
OrderUserId = p.o.OrderUserId,
OrderTeamID = p.o.OrderTeamID,
OrderUserNickName = p.o.OrderUserNickName,
DeviceName = d.DeviceName,
DeviceAddress = d.DeviceAddress,
DeviceZone = d.DeviceZone
});
var model_order_user_device_team = model_order_user_device.GroupJoin(model_team, o => o.OrderTeamID, t => t.TeamId, (o, t) => new { o, t }).SelectMany(p => p.t.DefaultIfEmpty(), (p, t) => new OrderModel()
{
OrderDeviceId = p.o.OrderDeviceId,
OrderId = p.o.OrderId,
OrderUserId = p.o.OrderUserId,
OrderTeamID = p.o.OrderTeamID,
OrderUserNickName = p.o.OrderUserNickName,
DeviceName = p.o.DeviceName,
DeviceAddress = p.o.DeviceAddress,
DeviceZone = p.o.DeviceZone,
TeamSerisNumber = t.TeamSerisNumber,
});
var model = model_order_user_device_team.GroupJoin(sub_model, o => o.OrderId, s => s.SubOrderParentId, (o, s) => new { o, s }).SelectMany(p => p.s.DefaultIfEmpty(), (p, s) => new OrderModel()
{
OrderDeviceId = p.o.OrderDeviceId,
OrderId = p.o.OrderId,
OrderUserId = p.o.OrderUserId,
OrderTeamID = p.o.OrderTeamID,
OrderUserNickName = p.o.OrderUserNickName,
DeviceName = p.o.DeviceName,
DeviceAddress = p.o.DeviceAddress,
DeviceZone = p.o.DeviceZone,
GoodsCount = sub_model.Where(sub => sub.SubOrderParentId == p.o.OrderId).Sum(sub => sub.SubOrderGoodsNumber),
});
GroupJoin前面部分是左连的集合，里面的参数分别是右边的集合、左边集合的外键、右边集合的主键、两个集合的对象、查找的集合。
写的不好，如何有何问题，大家可以一起讨论，这个只是作为笔记使用而已。
标签：highlight lambda表达式 == border 使用 完整 count ice mod
原文地址：https://www.cnblogs.com/zunzunQ/p/11811285.html
