Winston{yw}

For those who are on Windows, but yet wish to install Ruby Thin Server on your PC, here’s a short how-to.

Ruby Thin Server requires the following dependencies:

• Rack
• EventMachine

Unfortunately, the latest version of EventMachine (0.10.0 at the time of this post) is not a Win32 binary release, so it’s a hassle trying to get it installed on Windows. Instead, your best choice would be to download an earlier version of EventMachine 0.8.1, which is a Win32 binary release.

Even though it’s an earlier version, I have not encountered any problems with it. Of course, I am using Windows only for development purposes, and not for production purposes.

Install each dependency by following the steps below before you install Thin.

1. Install Rack.

c:\> gem install rack

2. Download EventMachine 0.8.1

Download. Install EventMachine locally.

c:\> gem install eventmachine -l

3. Install Ruby Thin Server, but ignore dependencies.

c:\> gem install thin --ignore-dependencies

Following these steps should install Ruby Thin Server successfully on your Windows machine.

Update from Google Groups:
Thin has been updated to install EventMachine 0.8.1 if you are on Windows. But you can always rely on the steps above if something fails.

Lately, I have been very much involved in the developmental aspects of MySQL, and searching by date or timestamp on a very large set of data is by far the most common task that I am required to do. Due to this, I was able to refresh my knowledge on MySQL and able to pick up some tips and tricks on working with date or timestamp in MySQL.

One of the helpful functions I found, was BETWEEN..AND… Previously, if I was extracting data between two dates, e.g. all records that occurred in the month of January, I would code my query like this:

select * from table_name
where created_at >= "2008-01-01" and created_at <= "2008-02-01;

However, the “greater than” and “lesser than” comparison can actually be replaced by a single function, BETWEEN..AND..:

select * from table_name
where created_at between "2008-01-01" and "2008-02-01;

Do note that the first date to be specified in the query MUST be earlier than the second date, else the query would simply return an empty set. Hope you won’t repeat the same mistake as I did.. I had to spend like 15 minutes looking at the query before I discovered the gruesome error.

In addition, if you look at the documentation, it states that:

If expr is greater than or equal to min and expr is less than or equal to max, BETWEEN returns 1, otherwise it returns 0. This is equivalent to the expression (min <= expr AND expr <= max) if all the arguments are of the same type.

Why then did I use “between ‘2008-01-01′ and ‘2008-02-01′” to extract all information that occurred within the month of January, and not “between ‘2008-01-01′ and ‘2008-01-31′”?

This is because, if the timestamp is not stated (i.e. only a date is used), MySQL automatically assumes a timestamp of 00:00:00 for the date. Hence, if I had used “between ‘2008-01-01′ and ‘2008-01-31′”, MySQL would have changed that to “between ‘2008-01-01 00:00:00′ and ‘2008-01-31 00:00:00′”, which clearly indicates that any record with a date of 2008-01-31 and timestamp greater than 00:00:00 would be excluded from the query. This is different from what we want, which is all the records in the month of January, 31st January inclusive.

Try this to verify that MySQL sets a timestamp of 00:00:00 for a date:

mysql> select current_date();

+----------------+
| current_date() |
+----------------+
| 2008-03-17     |
+----------------+
1 row in set (0.00 sec)

mysql> select timestamp(current_date());

+---------------------------+
| timestamp(current_date()) |
+---------------------------+
| 2008-03-17 00:00:00       |
+---------------------------+
1 row in set (0.00 sec)

Hopefully, this post has helped you to better understand how to use BETWEEN..AND.. to query your databases. In my subsequent posts, I will look at other useful MySQL functions.

Are you having problems upgrading your WordPress to version 2.3.3?

After following through the extended steps of upgrading WordPress, I encountered the following error on trying to access /wp-admin/upgrade.php:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@winstonyw.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Searching Google and the WordPress forums gave me an answer. Simply add the following two lines to the .htaccess file which should be residing in the blog’s root directory:

php_value memory_limit 32M
php_flag zend.ze1_compatibility_mode Off

Then, I was able to execute /wp-admin/upgrade.php successfully.However, for some reason, WordPress would overwrite .htaccess during the upgrade procedure, and so the two lines would be missing again. I had to add the two lines back to the .htaccess file before my blog is able to work.

Now I am back in business, after forsaking this blog for more than a year!