查找数值序列中的最大值
使用 Max 运算符可查找数值序列中的最高值。
示例 1
下面的示例查找任何员工的最近雇佣日期。
如果您对 Northwind 示例数据库运行此查询,则输出为:11/15/1994 12:00:00 AM
。
System.Nullable<DateTime> latestHireDate =
(from emp in db.Employees
select emp.HireDate)
.Max();
Console.WriteLine(latestHireDate);
Dim latestHireDate = Aggregate emp In db.Employees _
Into Max(emp.HireDate)
Console.WriteLine(latestHireDate)
示例 2
下面的示例查找任何产品的最大库存件数。
如果您对 Northwind 示例数据库运行此示例,则输出为:125
。
System.Nullable<Int16> maxUnitsInStock =
(from prod in db.Products
select prod.UnitsInStock)
.Max();
Console.WriteLine(maxUnitsInStock);
Dim maxUnitsInStock = Aggregate prod In db.Products _
Into Max(prod.UnitsInStock)
Console.WriteLine(maxUnitsInStock)
示例 3
下面的示例使用 Max 查找每个类别中单价最高的 Products
。 然后,按类别列出输出结果。
var maxQuery =
from prod in db.Products
group prod by prod.CategoryID into grouping
select new
{
grouping.Key,
MostExpensiveProducts =
from prod2 in grouping
where prod2.UnitPrice == grouping.Max(prod3 =>
prod3.UnitPrice)
select prod2
};
foreach (var grp in maxQuery)
{
Console.WriteLine(grp.Key);
foreach (var listing in grp.MostExpensiveProducts)
{
Console.WriteLine(listing.ProductName);
}
}
Dim maxQuery = From prod In db.Products() _
Group prod By prod.CategoryID Into grouping = Group _
Select CategoryID, _
MostExpensiveProducts = _
(From prod2 In grouping _
Where prod2.UnitPrice = _
grouping.Max(Function(prod3) prod3.UnitPrice))
For Each grp In maxQuery
Console.WriteLine(grp.CategoryID)
For Each listing In grp.MostExpensiveProducts
Console.WriteLine(listing.ProductName)
Next
Next
如果您对 Northwind 示例数据库运行上一个查询,所得到的结果将与如下内容类似:
1
Côte de Blaye
2
Vegie-spread
3
Sir Rodney's Marmalade
4
Raclette Courdavault
5
Gnocchi di nonna Alice
6
Thüringer Rostbratwurst
7
Manjimup Dried Apples
8
Carnarvon Tigers