asp.net - 如何在数据表的列中查找重复项并使用星号 asp.net vb 制作它们

Question

我有一个内存DataTable，我需要标记重复项.....例如..

从 到

我可能会做类似..

    For each dtrow in dt.rows
    If dtrow("Country") Is one of Duplicates then
            dtrow("Country") += "*"
    end if
    Next

抱歉问了这么多问题......我的头被烧毁了..什么都没出来..这个项目需要很快完成..

Answer 1

你可以使用LINQ-to-DataTable：

Dim dups = From row In dt.AsEnumerable()
           Let country = row.Field(Of String)("Country")
           Group row By country Into DupCountries = Group
           Where DupCountries.Count() > 1
           Select DupCountries
For Each dupCountryRows In dups
    For Each row In dupCountryRows
        row("Country") = row.Field(Of String)("Country") & "*"
    Next
Next

或者使用 C# 语法：

var dups = from row in dt.AsEnumerable()
           let id = row.Field<string>("Country")
           group row by country
           into DupCountries where DupCountries.Count() > 1
           select DupCountries;