将 VB Linq with Group by 和 Select 转换为 C#

Question

我正在尝试将以下 LINQ 代码从 VB.NET 转换为 C#，这是在数据表“tvp_dtl”上执行的。后跟VB代码。

Dim query
query = From row In tvp_dtl
        Group row By dataGroup = New With {
            Key .Tmall_txn_no = row.Field(Of String)("Tmall_txn_no"),
            Key .stock_code = row.Field(Of String)("stock_code"),
            Key .ItemNameLocalLang = row.Field(Of String)("ItemNameLocalLang"),
            Key .ItemUnitPrice = row.Field(Of String)("ItemUnitPrice"),
            Key .itemTotalAmount = row.Field(Of String)("itemTotalAmount")
        } Into Group
        Select New With {
            .Tmall_txn_no = dataGroup.Tmall_txn_no,
            .stock_code = dataGroup.stock_code,
            .ItemNameLocalLang = dataGroup.ItemNameLocalLang,
            .ItemUnitPrice = dataGroup.ItemUnitPrice,
            .itemTotalAmount = dataGroup.itemTotalAmount,
            .SumAmount = Group.Sum(Function(x) Integer.Parse(x.Field(Of String)("ItemNumber")))}

这里是我用C#写的版本

var query = from row in tvp_dtl
        group row by new
        {
            row.Tmall_txn_no = row.Field<string>("Tmall_txn_no"),
            row.stock_code = row.Field<string>("stock_code"),
            row.ItemNameLocalLang = row.Field<string>("ItemNameLocalLang")
        } into dataGroup
        select new
        {
            Tmall_txn_no = dataGroup.Field<string>("Tmall_txn_no"),
            stock_code = dataGroup.Field<string>("stock_code"),
            ItemNameLocalLang = dataGroup.Field<string>("ItemNameLocalLang"),
            ItemUnitPrice = dataGroup.Field<string>("ItemUnitPrice"),
            itemTotalAmount = dataGroup.Field<string>("itemTotalAmount"),
            SumAmount = dataGroup.Sum(x => int.Parse(x.Field<string>("ItemNumber") * int.Parse(x.Field<string>("QtyPerSet"))))
        };

但我认为这是不正确的。此外，我在使用“tvp_dtl”

时遇到此错误

Could not find the implementation of the query pattern for source type "DataTable". Group By not found

Answer 1

DataTable 不是 IEnumerable，更糟糕的是，它不提供编译器要求的方法来充当可枚举对象。

public class DataTable : MarshalByValueComponent, IListSource, ISupportInitializeNotification, ISupportInitialize, ISerializable, IXmlSerializable

幸运的是，有一种扩展方法可以解决这个问题。

试试这个：

var query =
    from row in tvp_dtl.AsEnumerable()

将 VB Linq with Group by 和 Select 转换为 C#

Convert VB Linq with Group by and Select to C#

linq

c#-to-vb.net

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