Developers Archive for February, 2007

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Mysql Random

Mysql Random Wednesday, February 28th, 2007

RAND(), RAND(N)

Returns a random floating-point value in the range between 0 and 1.0.
If a constant integer argument N is specified, it is used as the seed value, which produces a repeatable sequence of column values.

mysql> SELECT RAND();
-> 0.23232388898988
mysql> SELECT RAND(10);
-> 0.98989899999999
mysql> SELECT RAND(10);
-> 0.98989899999999
mysql> SELECT RAND();
-> 0.63553050033332
mysql> SELECT RAND(10);
-> 0.98989899999999

To obtain a random integer R in the range i SELECT * FROM tbl_name ORDER BY RAND();

ORDER BY RAND() combined with LIMIT is useful for selecting a random sample from a set of rows:

mysql> SELECT * FROM table1, table2 WHERE a=b AND c ORDER BY RAND() LIMIT 1000;

Note that RAND() in a WHERE clause is re-evaluated every time the WHERE is executed.

RAND() is not meant to be a perfect random generator, but instead is a fast way to generate ad hoc random numbers which is portable between platforms for the same MySQL version.

Posted in mysql database development | No Comments »

Status Bar Clock

Status Bar Clock Wednesday, February 28th, 2007

This JavaScript code will enable you to display a status bar clock. The status bar is the area at the bottom of a web page that displays various information, such as a web address or link information when you place your mouse over or click on a link.

Example displayed below in the status bar.

Place this code between your <HEAD> and </HEAD> tags:

<script Language=”JavaScript”>
<!– Script courtesy of http://www.web-source.net - Your Guide to Professional Web Site Design and Development
// Navigation - Stop
// Netscapes Clock - Start
// this code was taken from Netscapes JavaScript documentation at
// www.netscape.com on Jan.25.96

var timerID = null;
var timerRunning = false;

function stopclock (){
if(timerRunning)
clearTimeout(timerID);
timerRunning = false;
}

function showtime () {
var now = new Date();
var hours = now.getHours();
var minutes = now.getMinutes();
var seconds = now.getSeconds()
var timeValue = “” + ((hours >12) ? hours -12 :hours)
timeValue += ((minutes < 10) ? “:0″ : “:”) + minutes
timeValue += ((seconds < 10) ? “:0″ : “:”) + seconds
timeValue += (hours >= 12) ? ” P.M.” : ” A.M.”
window.status = timeValue;
// you could replace the above with this
// and have a clock on the status bar:
//
timerID = setTimeout(”showtime()”,1000);
timerRunning = true;
}

function startclock () {
// Make sure the clock is stopped
stopclock();
showtime();
}

// –>
</script>

Place the bold code within your <BODY> tag:

<BODY onLoad=”startclock()”>

Place this code below your <BODY> tag:

<form name=”clock” onSubmit=”0″>

Posted in Javascripts | No Comments »

mb_substr

mb_substr Wednesday, February 28th, 2007

- It is used to get part of string
- mb_substr performs multi-byte safe substr() operation
Parameters
string mb_substr ( string str, int start [, int length [, string encoding]])

1. Str - String to find the substring
2. start - Starting position of sub-string
3. Length - Length of sub-string to return
4. encoding - encoding

- Encoding parametr is optional, if we didn’t specify that php will automatically take internal encoding.

Example:

$str = “Test Test”;
echo mb_substr ( $str, 0 , 4, ‘UTF-8′);

Posted in Beginners Php / Php Novices | No Comments »

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