How to work with multiple results set using DataSet?

Introduction

ADO.NET is a mechanism to communicate with the database. It allows us to work in connected (database connection is alive while the operation is performed) as well as disconnected architecture (database connection is closed and operation can be performed on the data).

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In order to retrieve more than one result sets from the Stored Procedure or multiple select statements at one go
using DataSet, we can use this approach.

Below is the GridView code on my ASPX Page

ASPX PAGE

<asp:GridView ID="GridView1" runat="server" EnableViewState="false" />
 <hr />
 <asp:GridView ID="GridView2" runat="server" EnableViewState="false" />

In the above code snippet, we have two GridViews.

CODE BEHIND

 string _connStr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
 
protected void Page_Load(object sender, EventArgs e)
{
    DataSet dSet = new DataSet();
 
    // get the connection
    using (SqlConnection conn = new SqlConnection(_connStr))
    {
        // write the sql statement to execute
        string sql = "SELECT AutoID, FirstName, LastName FROM PersonalDetail ORDER BY FirstName; " +
                    "SELECT AutoId, FileName FROM Files Order By FileName ASC";
            // instantiate the command object to fire
 
           using (SqlCommand cmd = new SqlCommand(sql, conn))
           {
               using (SqlDataAdapter ad = new SqlDataAdapter(cmd))
               {
                   ad.Fill(dSet);
 
                   // 1st result set
                   GridView1.DataSource = dSet.Tables[0];
                   GridView1.DataBind();
 
                   // 2nd result set
                   GridView2.DataSource = dSet.Tables[1];
                   GridView2.DataBind();
                 }
            }
       }
   }

In the code behind, we have used DataSet to execute a SQL statement that has two SELECT statements separated by semi-column (;) (Multiple select statements returns multiple result sets from the database). 

DataSet is a collection of DataTables that can hold multiple result sets, so we have used DataSet here. Instead of the SQL statement, we can also use a stored procedure that can return multiple result set by executing multiple select statements.

All the select statements executed will have a separate DataTable created into the DataSet and we can
access them by using the indexer of the Tables collection (like we have used dSet.Tables[0] and
dSet.Tables[1] to return the 1st and the 2nd result set).

OUTPUT

My output looks like above picture.

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