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Closing Database connections

Mike Jenkins
Ranch Hand

Joined: Jul 23, 2006
Posts: 57
I have a Pagination using Scriptlet that works great where I am using two database connections to the MySQL database. Now I want to close the connections correctly but cant seem to figure out the best way to do it. I assume for JSP this is okay to open up the database connections the way this program is running but was wondering how do I correctly close the connections.

My attempt below seems to freeze the page where it wont come up.
Please advise because I have tried several attempts of closing the connections but everytime the page doesnt come up. If I get rid of my try/catch/finally blocks the page works great.


[ May 12, 2007: Message edited by: Mike Jenkins ]
Herman Schelti
Ranch Hand

Joined: Jul 17, 2006
Posts: 387
hi Mike,

you code does not compile anymore if you define ocon etc inside the catch block. Define them before the try block.

Herman
PS: this page is just for studying right?
If not have a look at http://displaytag.sourceforge.net/11/
Mike Jenkins
Ranch Hand

Joined: Jul 23, 2006
Posts: 57
Thanks,

It now works great and thanks for solving my problem. This is a real web page and is not for study. I working with a very small MySQL database that has 1000 records taking up less than 1 MB of space. I cant download any display tag library due to the environment and limitations I am in so I have to manually create this Pagination.
Can someone advise if the way I am doing my Pagination is efficient where I connect to the database 2 times and have to close it 2 times. Is there a better way to do it?
[ May 14, 2007: Message edited by: Mike Jenkins ]
Herman Schelti
Ranch Hand

Joined: Jul 17, 2006
Posts: 387
hi Mike,

You can use the first connection object ("ocon") for both select-statements, so you don't need the second one (the "con").

If the data in your database doesn't change much, you could store the results in the session-scope from the user or even in the applicationcontext-scope (if you have enough memory for that).
So you just have to do the sql-query once.

Herman

PS: your code would be even more efficient if you would use connection-pooling. Your application-server probably provides that.
Or use the JSP for the view only, instead of using it for backend-stuff

And what about those limitations? Does your company not allow you to use well-tested and well-known open-source software?
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: Closing Database connections