Coding

VARCHAR vs TEXT Performance

May 21, 2011 by Webhead

Ever wonder if VARCHAR(255) or TEXT is a better data type? This thread suggests VARCHAR(255) is better because it is allowed to use MEMORY (or RAM). The TEXT data type is not allowed in there.

http://forums.mysql.com/read.php?24,105964,105964#msg-105964

Although it was also found that a larger VARCHAR like VARCHAR(3000) has worse performance than TEXT (in MyISAM).

http://nicj.net/2011/01/20/mysql-text-vs-varchar-performance

The general rule appears to be to use VARCHAR if it is less than 255 characters and to use TEXT if it’s 255 or more.

If you need to optimize or find out how a MySQL query is doing, type in “EXPLAIN” before the query and you’ll get a table that shows a bunch of statistics. I’m not going to try to explain them all. It can be found on the MySQL docs site:

http://dev.mysql.com/doc/refman/5.0/en/explain-output.html

Favicon

May 17, 2011 by Webhead

Problem

When the simplest things don’t work it can drive you nuts. I had a task to add a favicon to a website so that it shows in the browser. To do this all I thought I had to do was get the PNG, convert it to a .ICO file on one of the many online converters and place it in the home directory of the website. What do you do when the image shows at http://mydomain.com/favicon.ico but doesn’t show as the browser’s page icon?

Solution

Clear the browser cache
Make sure you have the link tag in the <head> part
```
<link REL="SHORTCUT ICON" HREF="/favicon.ico">
```
Go here and make sure your icon is up to the standards

When I looked at Firebug I saw that there was a tag <link rel=”icon” href=”” type=”image/x-icon” >. I thought it was a little strange, but I also thought Firebug was just interpreting the icon location since it wasn’t in the source code I was looking at. (Firebug shows the real-time values of elements instead of the actual code. ie. if you use javascript to move an element, it will show the new coordinates instead of the original ones).

After a while, I found the website that validates favicons. Once I saw that extra “image/x-icon” again, I looked through my PHP code and saw that it was including that, which is why I didn’t see it in the main html code.

Creating an Instance of a PHP Class

May 15, 2011 by Webhead

Problem:

This works in PHP 5.3+:

$CLASS_NAME = 'TheName';

$class_instance = new $CLASS_NAME;

This doesn’t

define('CLASS_NAME', 'TheName');

$class_instance = new CLASS_NAME;

Workaround:

Use the way that works. There are other limitations with using a variable to create a class. Another way to create a class from a variable is by using:

$test = call_user_func(array($className, 'getInstance'));

No table-cell or table-row in IE CSS

May 13, 2011 by Webhead

Internet Explorer, How do I loathe thee?
Let me count the ways.

As stated on the w3schools website,

[quote]The values “inline-table”, “run-in”, “table”, “table-caption”, “table-cell”, “table-column”, “table-column-group”, “table-row”, “table-row-group”, and “inherit” is not supported in IE7 and earlier. IE8 requires a !DOCTYPE. IE9 supports the values.[/quote]

I had a project where I needed to create a photo gallery. The goal was to get the gallery to look like iStockPhoto with the images all bottom-aligned, evenly spaced, etc, etc. Well in creating the gallery I had a hard time aligning the photos on the bottom, so I took a look at how istock did it. They use “table-cell” display option and vertically align the image to the bottom. So I tried it, but soon found that Internet Explorer does not support that option. And then I found that istock was no exception.

iStock with Chrome

: iStock with IE

Solution:

I did not personally do this solution as this was not too important. However someone on Stack Overflow seems to have solved it with jQuery:

$(document).ready(function(){
  if ($.browser.msie && $.browser.version == 7)
  {
    $(".tablecell").wrap("<td />");
    $(".tablerow").wrap("<tr />");
    $(".table").wrapInner("<table />");
  }
});

the above script assumes you have divs using style such as:

<style>
.table     { display: table; }
.tablerow  { display: table-row; }
.tablecell { display: table-cell; }
</style>

Get All rows into One String