相关疑难解决方法(0)

如何在LINQ中执行GroupBy多列

SQL中与此类似的东西:

SELECT * FROM <TableName> GROUP BY <Column1>,<Column2>

如何将其转换为LINQ:

QuantityBreakdown
(
    MaterialID int,
    ProductID int,
    Quantity float
)

INSERT INTO @QuantityBreakdown (MaterialID, ProductID, Quantity)
SELECT MaterialID, ProductID, SUM(Quantity)
FROM @Transactions
GROUP BY MaterialID, ProductID

我正在尝试在vb.net中编写一个linq到对象查询,这是我正在尝试实现的c#版本(我在linqpad中运行它):

void Main()
{
 var items = GetArray(
        new {a="a",b="a",c=1}
        , new {a="a",b="a",c=2}
        , new {a="a",b="b",c=1}
    );

 (
  from i in items 
  group i by new {i.a, i.b} into g
  let p = new{ k = g, v = g.Sum((i)=>i.c)}
  where p.v > 1
  select p
 ).Dump();
}
// because vb.net doesn't support anonymous type array initializer, it will ease the translation
T[] GetArray<T>(params T[] values){
  return values;
}

我很难使用不同的语法组(vb在某些地方需要'identifier = expression',以及带''表达式'的求和算子')

非常感谢你的帮助!