[英]Linq .GroupBy() with count
我有一个表,需要在报告中进行总结。 这是我的样本表。
Orders
_____________________________________
CustomerId | CustomerName | OrderType
___________|______________|__________
1 | Adam | Shoe
1 | Adam | Shoe
1 | Adam | Shoe
1 | Adam | Hat
1 | Adam | Hat
2 | Bill | Shoe
2 | Bill | Hat
3 | Carl | Sock
3 | Carl | Hat
我试图对此进行总结,以便不循环地返回我的视图模型。 这是我试图实现的结果。
CustomerName | Shoe | Hat | Sock | Total Orders
------------ | ---- | --- | ---- | ------------
Adam | 3 | 2 | 0 | 5
Bill | 1 | 1 | 0 | 2
Carl | 0 | 1 | 1 | 2
//var resultList = dbContext.Orders.OrderBy(o => o.CustomerId);
如何使用GroupBy和Count达到期望的结果? 那是最好的方法吗?
var summary = from order in dbContext.Orders
group order by order.CustomerId into g
select new {
CustomerName = g.First().CustomerName ,
Shoe = g.Count(s => s.OrderType == "Shoe"),
Hat = g.Count(s => s.OrderType == "Hat"),
Sock = g.Count(s => s.OrderType == "Sock"),
TotalOrders = g.Count()
};
如果项目是固定的:
public List<OrderViewModel> GetCustOrders()
{
var query = orders
.GroupBy(c => c.CustomerName)
.Select(o => new OrderViewModel{
CustomerName = o.Key,
Shoe = o.Where(c => c.OrderType == "Shoe").Count(c => c.CustomerId),
Hat = o.Where(c => c.OrderType == "Hat").Count(c => c.CustomerId),
Sock = o.Where(c => c.OrderType == "Sock").Count(c => c.CustomerId),
Total = o.Count(c => c.CustomerId)
});
return query;
}
使用SQL是一种选择,我对其进行了测试并获得了您想要的:
select p.*, t.total as 'Total Orders' from
(
select CustomerName, count(CustomerId) total from Orders group by CustomerName
) as t inner join
(
select * from Orders
pivot(count(CustomerId)
for OrderType in ([Shoe], [Hat], [Sock])
) as piv
)as p on p.CustomerName = t.CustomerName
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.