Saving data using mysqli instead of mysql


I’m having trouble saving the data in the MySQL database since mysql_query function is not supported anymore.
In update.php, I’m now trying to use for example:
function delete_row($rowId){
$d_sql = “DELETE FROM airlines WHERE id=”.$_POST[$rowId.“_c0”].“;”;
$conn = mysqli_connect($mysql_host, $mysql_user, $mysql_pasw, $mysql_db);
$resDel = $conn->query($d_sql);
return “delete”;
But it doesn’t work…

On another hand, I don’t have any difficulty loading data from the server using mysqli_connect and $conn->query.

What PHP / SQL function should I use…

Thank you for your help!