[Mono-list] Questions about coding style

[Stifu]

To add to what Jonathan said, trying to reuse the same connection for
everything can also lead to concurrent access issues, if more than one
thread accesses the connection at a given time. I've seen such issues when
using Entity Framework. Besides, creating a new connection is really cheap.


Jonathan Pryor wrote
> 
> On Aug 20, 2012, at 3:28 PM, Philippe Grohrock <philippe.grohrock@>
> wrote:
>> Thanks for the reply already and I'm sorry, I should've added the lines
>> of code.
>> 
>> 	static class GlobalVariables
>> 	{
>> 		public static MySqlConnection connection = new connection();
>> 	}
>> 
>> This way the whole program has access to it and can modify/query the DB
>> when needed (this is what I meant with global).
> 
> I believe that this is a Bad Idea™.
> 
> Firstly, this is counter to ~every MSDN example on using connections,
> which always scopes the Connection instance:
> 
> 	//
> http://msdn.microsoft.com/en-us/library/ff647768.aspx#scalenetchapt12_topic9
> 	using (SqlConnection conn = new SqlConnection(connString))
> 	{
> 		conn.Open();
> 		// ...
> 	}
> 
> This implies that you should instead do:
> 
> 	static class Database {
> 
> 		internal static MySqlConnection CreateConnection ()
> 		{
> 			return new connection ();
> 		}
> 	}
> 
> And narrowly scope your use:
> 
> 	using (var c = Database.CreateConnection ()) {
> 		c.Open ();
> 		// ...
> 	}
> 
> Now, _why_ should you do this? Unfortunately I can't find anything to
> confirm or deny the following, but this is my recollection from using SQL
> many years ago...
> 
> The reason why is connection-related errors: if (when) you hit a network
> interruption, the DbConnection instance is unusable afterward, even if the
> network came back. (Though maybe I needed to .Close() and .Open() to
> repair the instance? I no longer remember.) I found that the
> easiest/sanest way to go was to just recreate the Connection instance when
> needed, and Dispose() of it as soon as possible (relying on lower-level
> connection pooling if possible).
> 
>  - Jon
> 
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