Tech.Bitez

Count number of words in a MySQL column

Wasif — Tue, 01 Jul 2008 17:36:15 +0000

It is a common requirement to count number of words in a column of a MySQL database table. But MySQL does not have any built in function to count number of words as it usually has for number of purposes.

But you can do it without it with a simple trick e.g. you have a column name and want to count number of words in it. This query will return number of words separated with space in a column

SELECT SUM( LENGTH(name) - LENGTH(REPLACE(name, ' ', ''))+1)
FROM table

If you want to count number of words separated by some other string for example comma (,) or semicolon (;), simply replace space with your required character.

MySQL GUI Tools

Wasif — Thu, 01 May 2008 10:31:45 +0000

I am creating a list of MySQL GUI tools. I hope you will contribute this list.

A wide variety of MySQL GUI tools are available in the market. Most of them are free but some are paid as well. We can divide GUIs in 2 categories i.e. desktop and web based applications. Here is the list of popular MySQL GUI tools I have heard of

Desktop Application
- Official MySQL GUI Tools
- HeidiSQL
- Navicat (Linux, Windows, Mac OS X)
- SQLyog
- CocoaMySQL (Mac OS X)
- SQL-Front
- Toad for MySQL
Web Based Application
- phpMyAdmin
- MySQL Quick Admin

If you know any good GUI Tool, please let me know.

Should we use template engines in PHP?

Wasif — Thu, 01 May 2008 08:50:40 +0000

I came across this discussion today on pros and cons of using template engines in PHP.

child pid 2299 exit signal File size limit exceeded (25)

Wasif — Sun, 30 Mar 2008 15:30:44 +0000

Today I found that Apache on my server was very slow and a lot of child pid xxxx exit signal File size limit exceeded (25) errors in error_log.

I simply searched for large (2gb) log files and deleted them. Everything became normal.

Increasing file upload limit in PHP

Wasif — Fri, 14 Mar 2008 19:10:40 +0000

There are different options to increase file upload limit in PHP. First is changing PHP configuration file (php.ini) and restarting webserver or overwriting the php.ini value in .htacces (this option is available if you are running Apache).

There are 2 directives which affect upload limit i.e. upload_max_filesize and post_max_size.

Now we look at the first method. First you have to find out where the php.ini is. To find out the location, make a .php file containing only this code and place it in your webroot and point your browser to this file.

 phpinfo(); ?>

In the page output you can find Configuration File Path. Open this file and change the values for upload_max_filesize and post_max_size according to your requirement e.g. to set 10MB upload limit, the values will be
upload_max_filesize = 10M
post_max_size = 10M

After changing the values, save php.ini and restart the webserver. If you open up the above PHP file again, you'll see the updated values of upload_max_filesize and post_max_size.

In case you don't have access to php.ini (in shared hosting environment) or don't want to restart the webserver then the best option is to use .htaccess.

The syntax for .htaccess as follows
php_value upload_max_filesize 10M
php_value post_max_size 10M

Apache supports .htaccess. I am not sure if you can overwrite these settings in .htaccess with lighttpd.

Saving images in MySQL with PHP

Wasif — Wed, 18 Jul 2007 18:33:53 +0000

People have different opinions on saving images in database. Some says, "Why bother database if we can handle this by saving images to disk". I am agree with this;).

Most of the requirements can be fulfilled by saving the images to disk. This reduces the unnecessary load on MySQL.

Here is the small code to save the image in MySQL with the help of PHP.

Images are saved in MySQL as BINARY data. BINARY data can not be saved in varchar or char data types, for this purpose we need a data type which can handle binary data. BLOB columns are treated as binary strings (byte strings). The following table is fulfilling our requirements for a simple test with a BLOB field.

CREATE TABLE `images` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `image` BLOB NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM;

Now we have a MySQL table ready to store the image. Next steps are easy i.e.

Read the image
Encode the image data
Save binary data in DB

These 3 steps are performed with the following PHP code

$image = chunk_split(base64_encode(file_get_contents("image.jpg")));
$query = "INSERT INTO images (image) VALUES('$image')";
mysql_query($query) or die(mysql_error());
echo "Image id is ".mysql_insert_id();

Now we have saved the image in database successfully. The next step is to display the image.

// showimage.php
header('Content-type: image/jpeg');
$query = "SELECT image from images where id=1";
$rs = mysql_fetch_array(mysql_query($query));
echo base64_decode($rs["image"]);

Ohhh!!! You wanted to display the image in HTML page. No problem, call this file as a image in .e.g.



</span></a></span>Image Test<span style="color: #009900;"><span style="color: #000000; font-weight: bold;">

 

Displaying image from database
 
 src="showimage.php" />

Let me know if you need some more info on this topic.

Download data as csv using PHP

Wasif — Sat, 30 Jun 2007 23:05:50 +0000

This is a very simple example to download data in csv format using PHP and MySQL. I have used a table with two columns i.e. id and name.

The main point to download file is a proper use of header(). It has said many times in many places but I repeat here, "Make sure there must not be any sort of output (including whitespaces) before header()". We can also set a default file name for the file.

Here is the PHP code


// Connect to database
mysql_connect("localhost", "root", "root");
mysql_select_db("test");
 
// mention the file name to display in download prompt
$file_name = "download.csv";
 
header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename=\"$file_name\"");
header("Cache-Control: cache, must-revalidate");
header("Pragma: public");
 
// Output header
echo "Id,Name"."\n";
 
$result = mysql_query("SELECT * FROM test");
while($rs = mysql_fetch_array($result))
{
	echo $rs["id"].",";
	echo $rs["name"]."\n";
}
?>

Consider the followings when downloading a large csv file

PHP script may exceed maximum execution time. To prevent this, use set_time_limit() at top of the script.
Sometimes it is beneficial to use mysql_unbuffered_query() instead of mysql_query() for huge data.

If you find any problem with this code, please inform.

Note: Do not use "ID" in the start of CSV file. Doing so will result in an error "SYLK: File format is not valid" when opening this file in Microsoft Excel.

Enable register globals

Wasif — Sat, 16 Jun 2007 13:49:23 +0000

It is strongly recommended that you do not turn on the register_globals. But if you still want to turn on register_globals then follow these steps

Make a .php file containing only this code

 phpinfo(); ?>

And upload this file to your new server and open in the browser. In the page output find the value for 'register_globals'. If it is off, then you can solve this problem in the following ways

Turn on the register_globals in php.ini by
register_globals = On
(it will not be possible if you are on a shared web server)
Put extract($_REQUEST) on the top of every .php file.
Turn on register_globals using .htaccess make a text file with the name .htaccess and put the following code in it and upload to the root folder
php_flag register_globals on
If you already have a .htaccess file in your website, then simply put this code in it.

enable mod_rewrite in Apache 1.3+WinXP

Wasif — Mon, 28 May 2007 11:58:51 +0000

mod_rewrite provides an effective way to make short/friendly URLs and it also makes your site more attractive for search engine crawlers.

You can enable mod_rewrite for Apache 1.3 with the below steps easily.

First step
Remove '#' in front of
LoadModule rewrite_module modules/mod_rewrite.so
Make sure 'mod_rewrite.so' is available under 'apache installation directory/modules'.

Second step
Remove '#' in front of
AddModule mod_rewrite.c

Third step
Set AllowOverride to any of these
AllowOverride FileInfo Options
or
AllowOverride All

Rember, you will find 2 instances of AllowOverride. One like

Options FollowSymLinks
AllowOverride None

and the 2nd one similar to

Options Indexes FollowSymLinks MultiViews
AllowOverride None
Order allow,deny
Allow from all

Change the value in the 2nd instance.
Don't forget to restart Apache for these changes to take affect.

A cool mod_rewrite cheat sheet.