Lacisoft's » mysql

MySQL – Sort results in order by list

lacisoft — Tue, 01 Feb 2011 05:23:37 +0000

I needed today to sort a result set in MySQL after a list of id’s given. My original query was:

SELECT uid, pid FROM pages WHERE uid IN (15,17,21,87);

So the exact order of records i needed was 15, 17, 21, 87. But i wasn’t getting the results in this order. After digging around for a while i found the solution which is quite easy! I needed to alter my query a little bit to receive the desired order of results

SELECT uid, pid FROM pages WHERE uid IN (15,17,21,87) ORDER BY FIELD(uid, 15,17,21,81);

And voila, it works!

Importing large files into a MySQL database

lacisoft — Wed, 20 Jan 2010 11:54:39 +0000

From time to time i have to insert really large files into MySQL. And sometimes there are problems because you don’t have access to the mysql command line utility from the server to issue the source command (this lets you import dumps or sql files). So you have to use phpMyAdmin or some other web based utility.

But also too often one runs into the barriers set by PHP, specifically the configuration directives from php.ini: upload_max_filesize, memory_limit and post_max_size. If these are not set to a decent value you won’t be able to upload really large files and phpMyAdmin will fail. If you have access to these then you can modify them and you will have the ability to upload the files.

But if not there is another solution. Open your config.inc.php from the phpMyAdmin directory and search for the following setting:

$cfg['UploadDir']

If it is present then modify it to point to a directory within the phpMyAdmin directory (you can call it “uploads”) or if not you can add it. Something like this:

$cfg['UploadDir'] = ‘uploads’;

Then you have to make sure that the directory “uploads” exists in your phpMyAdmin installation directory.

That’s all, now when you want to import a file just upload it there (with an ftp client) in that folder and in phpMyAdmin at the import screen there will be a select with the sql files that exist in the directory. You can import this way really huge files.

Weekly article batch. Edition 1

lacisoft — Thu, 07 Jan 2010 14:26:56 +0000

I read many articles and most times i don’t bookmark them even if they are fairly good articles and can be useful in some situations. I thought i should save them somewhere, but they are not so important to be added to bookmarks.

So starting with this year i will publish a post with these articles every week on thursday. This way i can find them when i need them and also maybe some of you can find something interesting to read among them.

The order is arbitrary and some of the articles may be older then one week. The fact is that i read them this week so they get mentioned here this week.

Interesting articles this week:

15 useful jQuery plugins and tutorials – published by designer-daily.com, contains a good selection of jQuery plugins and tutorials
Exception handling in PHP – published by devshed.com, we all come across this: exception handling, a nice overview on the topic
MySQL : Using IF in a WHERE clause – published by electrictoolbox.com, although not a good solution – an IF is possible in a WHERE clause and i post this here only for reference – i not recommend using such solutions
Dive into HTML 5 – published by diveintohtml5.org, HTML 5 is here and this is a fairly good intro in it
13 Useful Code Snippets for WordPress development, published by webdesignledger.com, WordPress in more and more a part of our life and this article can be handy if we want to customize some of the things in WordPress
Speed matters , published by Dries Buytaert on buytaert.net , increasing latency will drive your visitors away as one Google research paper points it out. So think twice before adding a feature that hurts performance

3 books for building revolutionary web applications

lacisoft — Fri, 31 Oct 2008 10:14:46 +0000

So i read again. That is not news. But i wanted to share with you what i read lately. Below you can find 3 very good books that can help you if you want to build scalable and revolutionary web applications. Maybe you know some of them, maybe not, but here they are anyway:

Building Scalable Web Sites by Cal Henderson (published by O’Reilly) Amazon link
High Performance MySQL by Jeremy Zawodny and Derek J. Balling (publised by O’Reilly) Amazon link
Programming Collective Intelligence by Toby Segaran (published by O’Reilly) Amazon link