Question

When I have a SQLConnection within a using clause as illustrated below do I need to explicitly close the connection?

protected SqlConnection Connection 
{
    get
    {
       if (this.connection == null)
       {
           this.connection = new SqlConnection(this.ConnectionString);
       }
       if (this.connection.State != ConnectionState.Open)
       {
           this.connection.Open();
       }

       return this.connection;
    }
} 

using (SqlConnection connection = this.Connection)
{
    using (SqlCommand cmd = connection.CreateCommand())
    {
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandText = "....";

        using (SqlDataReader reader = cmd.ExecuteReader())
        {
            while (reader.Read())
            {
                etc
            }
        }
    }
}

Answer 1

No you don’t. The Dispose() method of a connection will call Close if the connection is already open.

You should also change your code as John Gathogo suggests to create a new connection object each time it needs one. Your code will fail as it is because the second time you try to use the connection it will already be disposed.

ADO.NET uses connection pooling to keep a pool of open connections which it provides to whoever calls Open. This means that creating and opening new connection doesn’t cost anything as long as there are available connections in the pool. Keeping a connection open for longer than necessary will degrade performance.