在LINQ中按格式分组 [英] Group by format in LINQ

问题描述

我有一个记录集rsTaxType，我想按一个字段V_TAX_TYPE_MCD分组以获取每个组中的max(D_EFFECTIVE_DATE).

我有以下查询，该查询在''Group grc By grc.V_TAX_TYPE_MCD Into Group''行中显示错误-
"范围变量名称只能从不带参数的简单名称或限定名称中推断出来".

有人可以帮我解决查询问题吗?

I have a recordset rsTaxType and i want to group by a field V_TAX_TYPE_MCD to get the max(D_EFFECTIVE_DATE) in each group .

I have the below query which gives error in line ''Group grc By grc.V_TAX_TYPE_MCD Into Group'' saying -
"range variable name can be inferred only from a simple or qualified name with no arguments ".

Can somebody help me in fixing the query ?

Dim grcOrders As DataTable = rsTaxType.DataSet.Tables(0)
Dim query = From grc In grcOrders.AsEnumerable() _
   Group grc By grc.V_TAX_TYPE_MCD Into Group _
   Select V_TAX_TYPE_MCD, maxdate = Group.Max(Function(grc) grc.D_EFFECTIVE_DATE

推荐答案

尝试一下

From grc In grcOrders.AsEnumerable() _
   Group By grc.V_TAX_TYPE_MCD Into maxdate = Max(grc.D_EFFECTIVE_DATE) _
   Select V_TAX_TYPE_MCD,  maxdate 

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