Question about open and close of MySqlConnection

Question

hi
    i'd like to ask a question.   
  MySqlConnection connection = newMySqlConnection(stringConnection);
                MySqlCommand cmd = connection.CreateCommand();
                connection.Open(); and i have a try catch. accoding to your opinion, i should put  connection.Close() in the block of try,or outside of block of try? according to you,if i open the connection and do not close,is it bad?or i open 2 times(using different istancse,like connection1 and connecton2),is it ok? thank u very muchbest regardsmartin  

Answer 1

This code will work in tests. But it will propably fail in a production environment. You don't even close the connection and that is bad enough. This is how you should never,
EVER work with disposeable objects!
try
MySqlConnection connectionLev = newMySqlConnection("server=P30LSIMUL;user id=root;database=cncp20l");
MySqlCommand cmd = connectionLev.CreateCommand();
connectionLev.Open();
Console.WriteLine("OK");
catch (Exception ex)
Console.WriteLine(ex.Message);
try
MySqlConnection connectionLev = newMySqlConnection("server=P30LSIMUL;user id=root;database=cncp20l");
MySqlCommand cmd = connectionLev.CreateCommand();
connectionLev.Open();
Console.WriteLine("OK");
catch (Exception ex)
Console.WriteLine(ex.Message);
If code like that runs in any production environment, you are about to get fired.
From a catapult.
SqlConnections implement Finalize so when the GC does collect them, they will be properly closed. That can be anywhere between "milisccond the reference vanishes" and "the programm is closed after 100 years of the computer running without
a hitch and reboot."
Put one of those blocks (or both) into a loop that runs 100 times and you will run out of avalible SQL conenctions.
Since you alraedy have a try...catch block, just use the construct that Magnus showed you:
Put the variable outside of the try (so finalize can access it). Check for null (in case an exception happened before/during the creation, not during the use of it) then Dispose.
Note that finalize is even run after the function it is contained in returns (about the only code that can still run then). And that you should always log/expose ex.ToString(), never only the message (that one contains only 5% of the information, the otehr
95% are much more important).
More tips about exception handling:
http://www.codeproject.com/Articles/9538/Exception-Handling-Best-Practices-in-NET
Let's talk about MVVM: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/b1a8bf14-4acd-4d77-9df8-bdb95b02dbe2 Please mark post as helpfull and answers respectively.