compare select query (mysql).

gistfile1.txt

these queries are same run time.

select.php

<?php
$con = mysql_connect('localhost', 'root', 'passwd');
if (!mysql_select_db('sample_db')) {
     die('Could not select database: ' . mysql_error());
}
 
$sql = <<<EOF
select * from  ptable as p
inner join adtable as ad on p.pid = ad.pid
inner join atable as a on a.aid = ad.aid
where a.aid =
EOF;
 
// $sql = <<<EOF
// select * from adtable as ad
// inner join atable as a on a.aid = ad.aid
// inner join ptable as p on p.pid = ad.pid
// where a.aid =
// EOF;
 
// $sql = <<<EOF
// select * from atable as a, adtable as ad , ptable as p
// where a.aid = ad.aid
// and p.pid = ad.pid
// and a.aid =
// EOF;
 
// $sql = <<<EOF
// select * from adtable as ad, atable as a
// where a.aid = ad.aid
// and a.aid =
// EOF;
 
$time_start = microtime(true);
 
foreach (range(1,10000) as $id) {
     $_sql = $sql . $id;
     $result = mysql_query($_sql, $con);
     while ($row = mysql_fetch_array($result)) {}
}
 
$time = microtime(true) - $time_start;
echo "{$time} min.";