仅从数组中选择不同的值

Here, I have the following variable $countries_all:

Array ( 
  [0] => stdClass Object 
      ( 
          [countries] => India,Afghanestan,Japan,South Africa
      ) 
  [1] => stdClass Object 
      ( 
          [countries] => Singapore,South Africa,India,Pakistan
      )
  [2] => stdClass Object 
      ( 
          [countries] => Japan,Australia,India
      ) 
)

But i need to create second array $countries containing only unique values:

Array ( 
  [0] => stdClass Object 
      ( 
          [countries] => India
      )
  [1] => stdClass Object 
      ( 
          [countries] => Afghanestan
      )
  [2] => stdClass Object 
      ( 
          [countries] => Japan
      )
  [3] => stdClass Object 
      ( 
          [countries] => South Africa
      )
  [4] => stdClass Object 
      ( 
          [countries] => Singapore
      )
  [5] => stdClass Object 
      ( 
          [countries] => Pakistan
      )
  [6] => stdClass Object 
      ( 
          [countries] => Japan
      )
  [7] => stdClass Object 
      ( 
          [countries] => Australia
      ) 
)

For spliting by (,) i have used the below method

foreach ($countries_all as $list){
    $countrieslist=explode(',', $list->countries);
    foreach ($countrieslist as $uni_countries){
        echo $uni_countries;
    }
}

but how to get unique values, from the above case.

could anyone help me

Thanks in advance.

EDIT1

Here i have one more query related to above question.

Now i got the unique values,

how can i get results from database from that unique values

For example, i want all the results which are having(like) country as 'India'

The array_unique function is what you are looking for.

$countries = array();
foreach ($countries_all as $list){
    $countrieslist=explode(',', $list->countries);
    foreach ($countrieslist as $country){
        $countries[] = $country;
    }
}
$countries = array_unique($countries);

$newlist = array();
foreach ($countries_list as $list){
    $countrieslist=explode(',', $list->countries);
    foreach ($countrieslist as $uni_countries){
        echo $uni_countries;
        $newlist[] = $uni_countries){
    }
}
array_unique($newlist);

Try this:

$uniqueCountries = array();

foreach ($countries_list as $list){
    $countrieslist=explode(',', $list->countries);
    foreach ($countrieslist as $country){
        if (!in_array($country, $uniqueCountries)) {
            //adding to list
            $uniqueCountries[] = $country
        } else {
             echo $country, ' already in list', PHP_EOL;
        }
    }
}

$uniqueCoutries contains all found coutries, without duplicates

$commasplit = function ($list) { return explode(',', $list->countries); };
$countrieslist = array_unique(call_user_func_array('array_merge', array_map($commasplit, $countries_list)));

You may try this

$countrieslist = array();
foreach ($countries_all as $list){
    $countrieslist[] = explode(',', $list->countries);
}
$array = array_unique(array_reduce($countrieslist,'array_merge', array()));

An Example.