Question

In my project,i have one function to retrieve data from Sql2005 Server
like this,

SqlConnection sqlCnn = new SqlConnection("");
SqlCommand sqlCmd = new SqlCommand("Select user_id from users");
SqlDataReader sqlReader = null;

sqlCnn.Open();
sqlCmd.Connection = sqlCnn;
sqlReader = sqlCmd.ExecuteReader();

if (sqlReader.HasRows)
{
    while (sqlReader.Read())
    {
        if(user_id == 1)
        {
            SqlCommand sqlCmd2 = new SqlCommand("Select mobile from tbl");
            sqlCmd2.Connection = sqlCnn;
            sqlCmd2.ExecuteReader();
        }
    }
}

I got the following error when sqlcmd2 is executed.

There is already an open DataReader
associated with this Command which
must be closed first.

I don’t want to create a new sqlconnection at there. Is there any way to solve
this problem?

Answer 1

To open two readers per connection you need to enable MARS (multiple active result sets).
You can do this via connection string:

 Server=myServerAddress;Database=myDataBase;Trusted_Connection=True; MultipleActiveResultSets=true;

However, it is not recommended approach.
I’m sure you can retrieve the data you need with one query.

You need to explain what you need to retrieve, if you want and advice on a single query.
I assumed that the code you showed just a sample, not a real one, as it does not make much sense.

Look at ‘Is MARS all good news, or is there any downside?’ section here.