将数据表分组到单独的数据表中？

Question

我有一个像这样的 DataTable -

EmpId,Country 
1,Germany
2,Germany
3,UK
4,UK
5,UK
6,France
7,USA
8,USA

我想按国家/地区分组并将所有组提取到单独的数据表中。所以，我们 将有 4 个组/数据表。我该怎么做？

Stackoverflow 不允许我粘贴完整的工作代码。所以就到这里了，谢谢 @Myles B. Currie

测试代码 -

public void main()
   {
        DataSet ds = (DataSet) Dts.Variables["obj_Rs"].Value;
        DataTable dt = ds.Tables[0];

        List<DataTable> allCountryTables = new List<DataTable>();

        DataView view = new DataView(dt);
        DataTable distinctValues = view.ToTable(true, "Country");

        //Create new DataTable for each of the distinct countries 
        //identified and add to allCountryTables list

        foreach (DataRow row in distinctValues.Rows)
        {
            //Remove filters on view
            view.RowFilter = String.Empty;
            //get distinct country name
            String country = row["Country"].ToString();
            //filter view for that country
            view.RowFilter = "Country = " + "'" + country + "'";
            //export filtered view to new datatable
            DataTable countryTable = view.ToTable();
            //add new datatable to allCountryTables 
            allCountryTables.Add(countryTable);
        }//for each

        foreach(DataTable tbl in allCountryTables){

            String table = getDataTable(tbl);
            MessageBox.Show(table);

        }//for
}//main


    public static string getDataTable(DataTable dt){

        string table = "";

        foreach (DataRow dataRow in dt.Rows)
        {
            foreach (var item in dataRow.ItemArray)
            {
                table = table + item.ToString() + "|";
            }//for

            table = table + Environment.NewLine;

        }//for

        return table;

    }//method

Answer 1

当然不是执行此操作的最短方法，但既然您说您遇到 .Net 版本问题，那么完成这项工作还有很长的路要走。 （以下代码未经测试）

DataTable table; //Your Datatable
List<DataTable> allCountryTables = new List<DataTable>();

//Get distinct countries from table
DataView view = new DataView(table);
DataTable distinctValues = view.ToTable(true, "Country");

//Create new DataTable for each of the distinct countries identified and add to allCountryTables list    
foreach (DataRow row in distinctValues.Rows)
{
    //Remove filters on view
    view.RowFilter = String.Empty;
    //get distinct country name
    String country = row["Country"].ToString());
    //filter view for that country
    view.RowFilter = "Country = " + country;
    //export filtered view to new datatable
    DataTable countryTable = view.ToTable();
    //add new datatable to allCountryTables 
    allCountryTables.Add(countryTable);
}

Answer 2

这应该可以完成工作：

var countryGroups = dataTable.AsEnumerable()
    .GroupBy(row => row.Field<string>("Country"));

请记住添加以下引用： System.Data.DataSetExtensions

Answer 3

您可以使用 LINQ 为每个国家/地区创建数据表的子集：

Dim groups = From row In tblEmp
             Let country = row.Field(Of String)("Country")
             Group row By country Into Group
             Select Group.CopyToDataTable()
Dim allCountryTables = groups.ToList()

哎呀，我确定有一个 VB.NET 标记....

var groups = from row in tblEmp.AsEnumerable()
             let country = row.Field<string>("Country")
             group row by country into Group
             select Group.CopyToDataTable();
List<DataTable> allCountryTables = groups.ToList();