SQL / PHP PDO Select random row

Question

I want to be able to select a STUDENT randomly who has not FACED the exam ('N') and echo the name and subject. How can I achieve this?

$query = $db->prepare('SELECT name FROM exams WHERE faced = ?');
$array = array('N');
$query->execute($array);

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Rick James · Accepted Answer · 2018-05-07 21:37:09Z

9

You can use something like:

$query = $db->prepare('SELECT name, subject
          FROM exams WHERE faced = ?
          ORDER BY RAND() LIMIT 1');
$array = array('N');
$query->execute($array);

$result = $query->fetchAll(PDO::FETCH_COLUMN, 0);

var_dump($result);

edited May 7, 2018 at 21:37

Rick James

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answered Feb 18, 2014 at 12:42

ajtrichards

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3 Comments

Michael Arenzon Over a year ago

Just for the future: webtrenches.com/post.cfm/avoid-rand-in-mysql Try to avoid using this method, and maybe try something from the following post: stackoverflow.com/questions/4329396/…

Abhik Chakraborty Over a year ago

Yes RAND() is a recipe for killing mysql server !!

Rick James Over a year ago

If you have INDEX(faced) it won't be so bad. Even better would be a "covering" INDEX(faced, name, subject).

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