Question

Here’s a simplified version of my example:

using (DbCommand cmd = new SqlCommand("myProcedure", (SqlConnection)DataAccessHelper.CreateDatabase().CreateConnection()) { CommandType = CommandType.StoredProcedure })
{
    cmd.Connection.Open();
    using(IDataReader dr = cmd.ExecuteReader())
        doWork(dr);
}

When the command is disposed, is the connection closed? Or would I need to have that first using statement be for the connection, and then create the command in the closure?

Answer 1

If you want the reader to close the connection, you can use the overload of ExecuteReader():

...
using (IDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection)) 
...

By default, disposing a reader does not release the connection. – see MSDN for more info…

To address the question of Close() vs Dispose(), the MSDN states:

If the DbConnection goes out of scope, it is not closed. Therefore,
you must explicitly close the connection by calling Close or Dispose,
which are functionally equivalent.

Thus a self-closing connection need not be disposed necessarily. The main difference is that a closed connection can be re-opened, but a disposed connection cannot. The main additional work that Dispose() does is set internals to null which won’t have much of an effect since the connection is passing out of scope anyway.