how to find third maximum number from a number column(any table) in php? What is the query?

Question

i got this question in interview.

Answer 1

If you are asking about PHP arrays (not SQL table query), and the presupposition is that values in array can repeat (the array has non-unique values), then:

<?php
$ar = array( 1,4,6,7,8,1,4,5); // sample array
sort($ar); // values are sorted, they may repeat
$vals = array_count_values($ar); // values from $ar as indexes (now unique)
$keys = array_keys($vals); // array with unique values and following indexes
// third maximum value
echo $keys[count($keys)-3];
?>

you should also test if the 'count($keys)-3' exists, for example: if isset()..

note: small improvement, sorting $vals may be faster (smaller array), just rememer to sort keys not values:

<?php
$ar = array( 1,4,6,7,8,1,4,5);
$vals = array_count_values($ar); // values as indexes, not in ascending order
ksort($vals); // array sorting by keys
$keys = array_keys($vals);
echo $keys[count($keys)-3];
?>