Interview Questions → ADO.NET 2.0 → ADO.NET Questionnaire I

ADO.NET Questionnaire I

Can we sort data from a SQLDataSource when mode is set to DataReader?

No.A DataReader is a read only object. It is a quick way for reading through sequential data but you cannot go backwards through it.

Consider an example

<asp:SqlDataSource ID="SqlDataSource1" runat="server"
        ConnectionString="<your_connection_string>" 
	      DataSourceMode="DataReader"
        SelectCommand="SELECT * FROM [Subjects]">
</asp:SqlDataSource>
<asp:GridView ID="GridView1" runat="server" DataSourceID="SqlDataSource1" AllowSorting="true">
</asp:GridView>

Here grid view is bound using SqlDataSource control. When you run the program you can see the gridview with data in it. When you try to sort the records you will get following error.

The SqlDataSource 'SqlDataSource1' cannot sort. Set DataSourceMode to DataSet to enable sorting. If you are using a stored procedure that supports sorting, set the SortParameterName property to the name of the stored procedure's parameter that accepts a sort expression.

If you want to give sorting, paging and filtering like capabilities then change the DataSourceMode from DataReader to DataSet

How to merge 2 datatables?

if table1 and table2 are the instances of DataTable class then you can merge table2 in table1 using Merge method

table1.Merge(table2);

Posted By -

Karan Gupta

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