Having Clause

The HAVING clause is used in combination with the GROUP BY clause. It can be used in a SELECT statement to filter the records that a GROUP BY returns.

The syntax for the HAVING clause is:

SELECT column1, column2, ... column_n, aggregate_function (expression)
FROM tables
WHERE predicates
GROUP BY column1, column2, ... column_n
HAVING condition1 ... condition_n;

aggregate_function can be a function such as SUM, COUNT, MIN, or MAX.

Second Highest Salary

select max(salary)
from employee
where salary not in
(select max(salary)
from employee );

N'th Highest Salary

SELECT salary
FROM employee a
WHERE 3 = (
SELECT count( salary )
FROM employee b
WHERE a.salary <= b.salary )
LIMIT 0 , 30

Example Of CURL

/*
* Author: HBK
* Released: August 16, 2010
* Description: An example of the getWithCurl() function in order to grab contents from a website while.
*/

$url = 'http://www.google.com';

function getWithCurl($url)
{
$curl = curl_init();
// Setup headers - I used the same headers from Firefox version 2.0.0.6
// below was split up because php.net said the line was too long. :/
$header[0] = "Accept: text/xml,application/xml,application/xhtml+xml,";
$header[0] .= "text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5";
$header[] = "Cache-Control: max-age=0";
$header[] = "Connection: keep-alive";
$header[] = "Keep-Alive: 300";
$header[] = "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7";
$header[] = "Accept-Language: en-us,en;q=0.5";
$header[] = "Pragma: ";
// browsers keep this blank.

$referers = array("google.com", "yahoo.com", "msn.com", "ask.com", "live.com");
$choice = array_rand($referers);
$referer = "http://" . $referers[$choice] . "";

$browsers = array("Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.3) Gecko/2008092510 Ubuntu/8.04 (hardy) Firefox/3.0.3", "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1) Gecko/20060918 Firefox/2.0", "Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3", "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)");
$choice2 = array_rand($browsers);
$browser = $browsers[$choice2];

curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_USERAGENT, $browser);
curl_setopt($curl, CURLOPT_HTTPHEADER, $header);
curl_setopt($curl, CURLOPT_REFERER, $referer);
curl_setopt($curl, CURLOPT_AUTOREFERER, true);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_TIMEOUT, 30);
curl_setopt($curl, CURLOPT_MAXREDIRS, 7);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);

$data = curl_exec($curl);

if ($data === false) {
$data = curl_error($curl);
}

// execute the curl command
curl_close($curl);
// close the connection

return $data;
// and finally, return $html
}
// uses the function and displays the text off the website
$text = getWithCurl($url);
echo $text;
?>