Comparison between PHP and mysql variables

You can solve this problem by converting this string ( $row['block'] into an array with the function explode() and then comparing it with in_array() if the specified value ( $id ) exists in the list of blocked items. >

$blocks = explode(',', 'aa,bb,cc,dd');
$id = 'aa';

if(in_array($id, $blocks)){
    echo $id . ' existe em: $blocks';
}else{
    echo 'item não encontrado';
}

First you need to separate the values that are commas to only after that you can compare one by one, see;

$ids = explode(',', $rows['block']);
// a saída sera um array: ['aaa', 'bbb', 'ccc', 'ddd']

With ids separated, you can loop with foreach or use the in_array function native from PHP .

Using foreach :

foreach($ids as $id) {
    if ($id == $idBlock) {
        /*
            trate caso os ids sejam iguais
        */
    }
}

Using in_array :

if (in_array($idBlock, $ids)){
    /* O ID existe na lista em questão */
}

Look at the example if each id comes from multiple records:

if($th = $mysqli->query("SELECT * FORM 'sua_tabela'"){
    while($row = $th->fetch_assoc()){
       if ($rows['block'] == $idBlock ) {/
           //Seu código
       } else {
           //Seu código
       }
    }
}

This will make you go through all the records coming from the query, notice that I used object-oriented mode, that is, my variable $mysqli was created like this:

$mysqli = new mysqli('host', 'user', 'senha', 'db');

Now if your question is that every record already comes with the ids: "aa, bb, cc ..."

The correct thing to do is like the example of the other users below, using explode with foreach or in_array