将linq结果集转换为数据表

Question

var query = (from row in playerSpotAndValue.AsEnumerable()
             where !row.Field<string>("RunningTotal").Contains("/")
             group row by row.Field<UInt16>("SpotID") into spotID
             orderby spotID.Key
             select new
             {
                 SpotID = spotID.Key,
                 HandTotal= spotID.Max(p => Convert.ToUInt16(p.Field<string>("RunningTotal"))),
                 RowsCount = spotID.Count()
             }); 

How to use CopyToDataTable in this query so that i can query like this

query.CopyToDataTable().Rows[0]["HandTotal"].ToString();

Answer 1

Yes, you need to use the following extension method :

public static DataTable CopyToDataTable<T>(this IEnumerable<T> source) where T : DataRow

---

But first you need to have IEnumerable<DataRow> but not of anonymous types.

Your table should have the columns you want to populate, then use DateTable.NewRow() method

Answer 2

Assuming that dtDealerTotal (orgininally referenced in your question) is the table in which you want to find the rows with SpotID from your query and you want to add the HandTotal result as DataColumn :

DataTable result = dtDealerTotal.Clone();
result.Columns.Add(new DataColumn("HandTotal", typeof(UInt16)));
var dealers = dtDealerTotal.AsEnumerable();
foreach (var x in query)
{
    foreach (var d in dealers.Where(dr => dr.Field<UInt16>("SpotID") == x.SpotID))
    {
        var fields = d.ItemArray;
        fields.Concat(new Object[] { x.HandTotal });
        result.Rows.Add(fields);
    }
}

Note : You can only use CopyToDataTable on existing DataRows, not on anonymous types. So you either need to select these rows first to copy them into a new DataTable or (when the schema is different like here, since you want to add HandTotal ) you need to create a new DataTable manually, which is what i did.

Answer 3

This is a way you can achieve, what you want .

Your LINQ query, and here is a function that return DataTable:

public static DataTable ToDataTable(DataContext ctx, object query) // ctx is your data context, & query is your linq query 
{
    IDbCommand cmd;

    try
    {
        cmd = ctx.GetCommand(query as IQueryable);
    }
    catch
    {
        throw new Exception("Could not connect database");
    }

    SqlDataAdapter adapter = new SqlDataAdapter();
    adapter.SelectCommand = (SqlCommand)cmd;
    DataTable dt = new DataTable();

    try
    {
        cmd.Connection.Open();

    }
    catch
    {
        cmd.Connection.Close();
        throw new Exception("Could not connect database");
    }

    try
    {
        adapter.Fill(dt);
        cmd.Connection.Close();
    }
    catch(Exception ex)
    {
        cmd.Connection.Close();
        throw new Exception("Query Parsing Error");
    }

    return dt;
}

Answer 4

query.First().HandTotal.ToString() 

This way I can find hand total in very first row and therefore I need not put my linq query result set in data table. I would like to say thank to Mr. kmp.