SQL / PHP PDO Select random row -

I'm new to PDO. I want to be able to choose a student who did not take the exam ('n') Has not echoed the name and the subject. How can I get it?

  $ query = $ db- & gt; Ready ('name of selection where the test encountered =?'); $ Array = array ('n'); $ Query-> Execute ($ array);  

You can use something like this:

  $ query = $ db- & gt; Ready ('selection name, subject to examination where faced? = Sequence by rand () range 1'); $ Array = array ('n'); $ Query-> Execute ($ array); $ Result = $ query- & gt; Obtain all (PDO :: FETCH_COLUMN, 0); Var_dump ($ result);