Question

I normally use DataSet because It is very flexible. Recently I am assigned code optimization task , To reduce hits to the database I am changing two queries in a procedure. one Query returns the count and the other returns the actual data. That is , My stored procedure returns two tables. Now, I know how to read both tables using DataSets, But I need to read both tables using DataReader. In search of that I found This.

I follow the article and wrote my code like this:

dr = cmd.ExecuteReader();
while (dr.Read())
{


}
if (dr.NextResult()) // this line throws exception
{
   while (dr.Read())
{

But I am getting an exception at dt.NextResult. Exception is :

Invalid attempt to call NextResult when reader is closed.

I also googled above error , but still not able to solve the issue.
Any help will be much appreciated. I need to read multiple tables using datareader, is this possible?

Answer 1

Try this because this will close connection ,data reader and command once task get over , so that this will not give datareader close exception

Also do check like this if(reader.NextResult()) to check there is next result,

using (SqlConnection connection = new SqlConnection("connection string here"))
{
    using (SqlCommand command = new SqlCommand
           ("SELECT Column1 FROM Table1; SELECT Column2 FROM Table2", connection))
    {
        connection.Open(); 
        using (SqlDataReader reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                MessageBox.Show(reader.GetString(0), "Table1.Column1");
            }

            if(reader.NextResult())
            {
               while (reader.Read())
              {
                MessageBox.Show(reader.GetString(0), "Table2.Column2");
              }
            }
        }
    }
}