Question

我正在尝试获取主数据表，并将数据的子集从其中拉入另一个表。我无法弄清楚如何使我的LINQ语法正确。

    static void Main(string[] args)
    {

        Console.WriteLine("start...");

        DataTable dt = new DataTable();
        dt.Columns.Add("fn", typeof(string));
        dt.Columns.Add("ln", typeof(string));
        dt.Columns.Add("EN", typeof(int));
        dt.Columns.Add("Role", typeof(string));

        Object[] rows = {
                             new Object[]{"Jane","Smith",123456,"Admin"},
                             new Object[]{"Jane","Smith",123456,"Test"},
                             new Object[]{"Jane","Smith",123456,"QA"},
                             new Object[]{"John","Doe",23456,"Admin"},
                             new Object[]{"John","Doe",23456,"Test"},
                             new Object[]{"John","Doe",23456,"Manager"},
                             new Object[]{"John","Doe",23456,"Approver"},
                             new Object[]{"Princess","Peach",12345,"Admin"},
                             new Object[]{"Princess","Peach",12345,"Test"},
                             new Object[]{"Princess","Peach",12345,"QA"}
                         };

        foreach(Object[] row in rows)
        {
            dt.Rows.Add(row);
        }


        DataTable o = dt.AsEnumerable()
            .Where(x => x.Field<string>("EN") == 123456)
            .CopyToDataTable();

        for(int i =0; i <o.Rows.Count-1; ++i)
        {
            for(int x=0; x<o.Columns.Count; ++x)
            {
                Console.Write("{0}\t", o.Rows[i][x].ToString());
            }
            Console.WriteLine();
        }


        Console.WriteLine("fin...");
        Console.ReadLine();

    }

所以我想要的结果是Jane Smith的记录。我也尝试过使用

DataTable.Select("EN = 123456");

但这会返回一个DataRow []，我真的希望它在一个表对象中。

Answer 1

你需要：

DataTable o = dt.AsEnumerable()
                .Where(x => x.Field<int>("EN") == 123456)
                .CopyToDataTable();

由于该字段的类型为int。

您还可以比较名字和姓氏：

DataTable o = dt.AsEnumerable()
    .Where(x => x.Field<string>("fn") == "Jane" &&
                x.Field<string>("ln") == "Smith")
    .CopyToDataTable();

如果要执行不区分大小写的比较，请使用String.Equals重载并提供适当的StringComparison值。

datatable到datatable linq过滤器

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