Do I need to close SQL Server connection with the using keyword?

[Davidpk]

I keep finding conflicting results for this question. Let's look at this C# code of running an SQL query:\[code\]using (SqlConnection cn = new SqlConnection(strConnectString)){ cn.Open(); using (SqlCommand cmd = new SqlCommand(strSQL, cn)) { cmd.ExecuteNonQuery(); } //Do I need to call? cn.Close();}\[/code\]Do I need to call that last \[code\]cn.Close()\[/code\]? The reason I'm asking is that in a heavy traffic web app I run out of connections in a pool.