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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