Check if a specific value exists at a specific key in any subarray of a multidimensional array

Question

I need to search a multidimensional array for a specific value in any of the indexed subarrays.

In other words, I need to check a single column of the multidimension

Answer 1

If you have to make a lot of "id" lookups and it should be really fast you should use a second array containing all the "ids" as keys:

$lookup_array=array();

foreach($my_array as $arr){
    $lookup_array[$arr['id']]=1;
}

Now you can check for an existing id very fast, for example:

echo (isset($lookup_array[152]))?'yes':'no';