title: Using SQLConnection across multiple methods ('using' keyword yes or no)
body: <p>I want to re-use the same SQLConnection accros different methods within the class. What I'm doing right now (testing only) is creating and opening a connection in the constructor:</p>
  
  <pre><code>SQLConnection Connection;
  
  Constructor(string connection_string)
  {
      this.Connection = new SqlConnection(connection_string);
      this.Connection.Open();
  }
  </code></pre>
  
  <p>then I use "this.Connection" inside methods and finally use this.Connection.Close() and Dispose() at the end when the object is not needed anymore. From what I know it would be cleaner to use 'using' inside each method like this (the constructor would only set the connection_string):</p>
  
  <pre><code>using (SqlConnection connection = new SqlConnection(connection_string)) {
   connection.Open(); ...
  }
  </code></pre>
  
  <p>Because of connection pooling, only one connection is actually used, despite the above 'using' line being placed in multiple methods (e.g. when they are called one after another), correct? However, wouldn't this create many SQLConnection instances where only one would be needed? E.g.:</p>
  
  <pre><code>MyClass obj(some_string);
  obj.Method1(); // calls 'using SqlConnection connection = new SqlConnection'
  obj.Method2(); // calls 'using SqlConnection connection = new SqlConnection'
  obj.Method3(); // calls 'using SqlConnection connection = new SqlConnection'
  </code></pre>
  
  <p>So what's the proper, optimal  way to share the SQLConnection?</p>