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POcalculating percentile for huge database
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2013-09-30T12:28:20.267
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2018-01-01T16:37:55.027
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i have huge database containing student information about test code and the marks achieved for those test code. I need to recompute percentile marks for students corresponding to each test codes. I have a code for a series of test code but it doesn't work properly. <pre><code>function recompute_percentiles() { if($_REQUEST[testcode]=="CAT B1" or $_REQUEST[testcode]=="CAT B2" or $_REQUEST[testcode]=="CAT B3" or $_REQUEST[testcode]=="CAT B4") { echo " Got testcode: ".$_REQUEST[testcode]; $getsortedq=mysql_query("SELECT username, section1right as m from kmarks where testcode='.$_REQUEST[testcode].' order by section1right DESC"); if(!$getsortedq) echo "Could not get the sorted query"; else echo "got the sorted query quick"; $totalcount=mysql_num_rows($getsortedq); while($r=mysql_fetch_array($getsortedq)) { $u=$r[username]; $m=$r[m]; $array[$u]=$m; } $array2=$array; //print_r($array2); $updated=0; foreach($array as $key=>$value) { $countsame=0; foreach($array2 as $k=>$v) { if($v>=$value) $countsame++; else break; } $countless = $totalcount - $countsame; reset($array2); $percentile=round($countless/$totalcount*100,2); $updatep1q=mysql_query("UPDATE kmarks set percentile1=$percentile where username='.$key.' and testcode='.$_REQUEST[testcode].'"); if(!$updatep1q) echo " Could not update p1 for username: ".$key; else $updated++; } echo " Updated ".$updated." records in kmarks db, out of ".$totalcount." records for testcode ".$_REQUEST[testcode]; } } </code></pre>
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<php><sql><percentile>
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calculating percentile for huge database
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1. USShandhanu Mohan
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