MySQL order by rand() optimization

Optimize Order by RAND() in MySQL

Where when are dealing with large databases, and you want to query you database using ORDER BY RAND(), you will your query is very slow. This article shows you how to speed up this kind of queries.

http://akinas.com/pages/en/blog/mysql_random_row/

Your optimized ORDER BY RAND() queries will be hundreds time faster now.

MySQL Data Types

I found a great link, where MYSQL Data Types are detailed. If you need to know just how much space each data type takes, you should read this great article about mysql data types. It will help you to create the best structure (optimized structure) for your database. The database structure and optimization is important when you deal with large amount of data(millions of records for example).


Here is the link http://www.peachpit.com/articles/article.aspx?p=30885&seqNum=7

Smarty format date

How to format date in Smarty

When you extract a date field from database, it is in the format yyyy-mm-dd. But maybe you want to list it other format, for example dd-mm-yyyy. You can retrieve this format directly from database, usign MySQL function DATE_FORMAT, or if you are using Smarty you can use date_format function.

Here is an example of Smarty date formatting:

{$smarty.now|date_format:"%d:%m:%Y"}

This will format current time, in dd-mm-yyyy format.
You can find all date conversions on smarty website.

Formatting dates using Smarty

Disabling magic quotes in PHP

How to disable magic quotes

You cannot disable magic quotes from .htaccess or php.ini, only from apache httpd.conf file.

You can use PHP to disable magic quotes at runtime. Here is the function:

if (get_magic_quotes_gpc()) {
function stripslashes_deep($value)
{
$value = is_array($value) ?
array_map('stripslashes_deep', $value) :
stripslashes($value);

return $value;
}

$_POST = array_map('stripslashes_deep', $_POST);
$_GET = array_map('stripslashes_deep', $_GET);
$_COOKIE = array_map('stripslashes_deep', $_COOKIE);
$_REQUEST = array_map('stripslashes_deep', $_REQUEST);
}

This function will strip slashes for all REQUEST values. If you make SQL queries with these values, you have to use mysql_real_escape_string function in order to prevent sql injection.


Disabling magic quotes, using Apache and PHP

Change text link in Javascript

How to change a link text in Javascript

Let's say you have a link, with the anchor text 'mylink', and you want to change this text using Javascript. For this we will use innerHTML attribute. Here it is:

document.getElementByID( 'mylinkid' ).innerHTML = 'my new link text';

You will probably need this if youn need to show/hide some html elements.

Changing text in a link using Javascript

Javascript explode function

Javascript function like PHP explode function

Looking for an explode function in Javascript? JS has such a function, called split. Split take a string, and splits it by a separator, then return an array containing the result. So it works just like explode PHP function.

Example:

var mystring = 'test explode split string';
var myarray = mystring.split(" ");

Split array would have 4 elements: test, explode, split, string.

So javascript split function is the equivalent of explode function in PHP.

Form Validation with PHP

Validating forms in PHP

Using validation class from PEAR http://pear.php.net/package/Validate, it's very easy to validate forms. Forms validation is neede in order to protect your website from xss injection, sql injection, email injection. For example if you are expecting an email address in a field, you should validate that field for an email address.

This class validation from PEAR has the following validation methods:

• number
• email
• date
• string
• and more

All you have to do is download this validation class from PEAR, and you now can have a safe website by validationg user input. Open downloaded class, and you will see all the methods, with all the parameters required for each validation method.

How to validate form submission in PHP

How to check if a text exists in a string

How to check if a substring exists in a string in PHP

Having a string:

$mystring = 'teststringforme';

I want to know if, for example, 'for' exists in $mystring. Using PHP function strpos, it's very easy.

if( strpos( $mystring, 'for' ) !== false )
{
echo 'string exists';
}
else
{
echo 'string does not exist';
}

Find if a text exists in a string using PHP

Replace string in MySQL

Replacing a string in MySQL

So you have hundreds of records in a table, and you want to replace a string in a single query.
You could use the REPLACE MySQL function. Here is your replace query:

UPDATE yourtable SET yourfield = REPLACE(yourfield,"some_string","some_new_string")
WHERE yourconditions.

This query replaces "some_string" with "some_new_string" in "yourfield" field. You can also add some conditions in WHERE statement.

How to replace a string in mySQL

How to parse CSV files in PHP

Parsing CSV files in PHP

CSV - comma separated values. Values in a CSV file are separated by comma.

Eg:

name, score
john, 10
brian, 5
jane, 8

So how do you get values from a CSV file in PHP? The easiest way to is to use PHP function fgetcsv . Read the documentation about this function, and there is also an easy example there.

Using CSV files, is a good option if you don't have access or you don't want to use a database. After you parse the CSV file, you can get the values in an array, and then display them any way you want on the web page.

PHP parse csv file

Sending mail with PHP

How to send mail using PHP

Using phpmailer class, you can send email with PHP very easy. You can download phpmailer from here. PHP has many options, mail can be sent using SMTP or php mail function. You can also add attachments, add BCCs, CCs and send HTML email. I've been using this class for a while, and I am very happy with it. Some examples can be found here.

Send mail in PHP tutorial

How to alternate row colors with php

Alternate colors in table rows with php

Alternating colors in php, it's simple. Here is the code:

foreach( $array_values as $value )
{
$counter++;
$background_color = ( $counter % 2 == 0 ) ? ('blue') : ('red');

echo '<tr><td style="background-color:'.$background_color.'">' . $value . '</td></tr>';
}

As you can see it's simple. If the current row number is even the color is blue, if the row number is odd, background color is red. This is just an example, you can alternate what colors you want using php. $array_values array can be an array coming from a database query.