Answers for "display error mysql php"

php show error

error_reporting(E_ALL);
ini_set('display_errors', 1);

php mysql error

mysqli_query($this->db_link, $query) or die(mysqli_error($this->db_link)); 
# mysqli_query($link,$query) returns 0 if there's an error.
# mysqli_error($link) returns a string with the last error message