Populate Data Table from Data Reader

Populate data table from data reader

You can load a DataTable directly from a data reader using the Load() method that accepts an IDataReader.

var dataReader = cmd.ExecuteReader();
var dataTable = new DataTable();
dataTable.Load(dataReader);

Populate multiple datatables from DataReader. Is it even possible?

Very old question, but in case someone else stumbles upon this... Found the answer in this SO answer: If you use DataTable.Load() then you should not use rdr.NextResult(), as that is taken care implicitly. Simply call .Load() for your next table. So, for example, if you have an expectedTableCount:

ds = new DataSet();
ds.Tables.Add("Table1");
ds.Tables[0].Load(reader);
for (int ii = 1; ii < expectedTableCount; ii++)
{
    ds.Tables.Add("Table" + (ii + 1));
    ds.Tables[ii].Load(reader);
}

How to read data from a data reader into a data table?

Missing the users.Add(user); at the end of each loop

    private IList<User> GetUsersFromDataTable(DataTable usersTable) 
    { 
        IList<User> users = new List<User>(); 
        foreach (DataRow row in usersTable.Rows) 
        { 
            User user = new User(); 
            user.UserID = (int)row["UserID"]; 
            user.Password = (string)row["Password"]; 
            user.Username = (string)row["Username"]; 
            users.Add(user);
        } 
        return users; 
    }

How to convert a datareader to datatable

Check this out:

Public Function ExecuteQuery(ByVal s As String, ByVal condb As SqlConnection, ByVal ParamArray params() As SqlParameter) As DataTable
        Dim dt As DataTable = Nothing
        Using da As New System.Data.SqlClient.SqlDataAdapter(s, condb)               
            dt = New DataTable
            If params.Length > 0 Then
                da.SelectCommand.Parameters.AddRange(params)
            End If
            If da.SelectCommand.Connection.State <> ConnectionState.Open Then da.SelectCommand.Connection.Open()
            da.Fill(dt)                    
        End Using
        Return dt
End Function

Trouble loading SQL Data Reader data into DataTable

Instead of a SqlDataReader, use a SqlDataAdapter.

SqlDataAdapter myAdapter = new SqlDataAdapter(command);
myAdapter.Fill(datatable);

With a SqlDataAdapter, you don't need to explicitly call SqlConnection.Open() and SqlConnection.Close(). It is handled in the Fill() method.

how read with datareader from datatable

Find a different control. That one is hard-coded to using an OdbcDataReader. You don't use a DataReader to read data from a DataTable - you iterate through the DataRows.

As a workaround, you could overload AddItems to accept a DataTable:

public void AddItems(DataTable dt, string textField, string valueField)
{
    ClearAll();
    int i = 0;
    foreach (DataRow dr in dt.Rows)
    {
        chkList.Items.Add(dr[textField].ToString());
        chkList.Items[i].Value = dr[valueField].ToString(); 
        i++;               
    }
}

Convert datatable to datareader

I know this is old, but the answers here seem to have missed the point of the OPs question.

DataTables have a method called CreateDataReader which will allow you to convert a DataTable to a DbDataReader object. In this case a DataTableReader.

DataTable table = new DataTable(); 
//Fill table with data 
//table = YourGetDataMethod(); 
DataTableReader reader = table.CreateDataReader();

I should point out that this will not increase performance since you should be using one or the other.

Here are some more resources on the matter:

• DataReader Vs DataTable
• Is datareader quicker than dataset when populating a datatable?

How to retrieve second resultset from DataReader to Datatable?

Until the reader is not closed you can load the further tables. If you have multiple results I suggest you to populate a DataSet, which can contain multiple DataTable instances:

public static DataSet ToDataSet(IDataReader reader)
{
    DataSet ds = new DataSet();
    while (!reader.IsClosed)
    {
        DataTable dt = new DataTable();
        dt.Load(reader);
        ds.Tables.Add(dt);
    }

    return ds;
}

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