There are situations in which you may want to extract the values from data source in a DataReader instance (calling the ExecuteReader() method for your OleDbCommand/SqlCommand command). That DataReader can be used for Telerik RadGrid source - all you need to do is relate this instance with the DataSource property of the control.
In the code sample below we use Access data source and OleDbDataReader:
| ASPX/ASCX |
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<rad:radgrid id="RadGrid1" runat="server" AutoGenerateColumns="true" /> |
And in the code-behind:
| C# |
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OleDbConnection conn = null;
OleDbDataReader reader = null;
private void RadGrid1_NeedDataSource(object source, Telerik.WebControls.GridNeedDataSourceEventArgs e)
{
RadGrid1.DataSource = ReadRecords("Select TOP 5 * FROM Customers", "Nwind.mdb");
}
private OleDbDataReader ReadRecords(string query, string dbFile)
{
conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath(dbFile));
conn.Open();
OleDbCommand cmd = new OleDbCommand(query, conn);
reader = cmd.ExecuteReader();
return reader;
}
private void RadGrid1_DataBound(object sender, System.EventArgs e)
{
reader.Close();
conn.Close();
} |
| VB.NET |
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Dim conn As OleDbConnection = Nothing
Dim reader As OleDbDataReader = Nothing
Private Sub RadGrid1_NeedDataSource([source] As Object, e As Telerik.WebControls.GridNeedDataSourceEventArgs) Handles RadGrid1.NeedDataSource
RadGrid1.DataSource = ReadRecords("Select TOP 5 * FROM Customers", "Nwind.mdb")
End Sub
Private Function ReadRecords(query As String, dbFile As String) As OleDbDataReader
conn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath(dbFile))
conn.Open()
Dim cmd As New OleDbCommand(query, conn)
reader = cmd.ExecuteReader()
Return reader
End Function
Private Sub RadGrid1_DataBound(sender As Object, e As System.EventArgs) Handles RadGrid.DataBound
reader.Close()
conn.Close()
End Sub |
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Note: the most appropriate place to close the DataReader and the connection is in the DataBound event handler of the grid. |