此代码不会将表单值插入数据库

Question

这是代码而不是插入数据库

mysqli_query($con, "INSERT INTO 'users' ('username', 'password', 'email', 'hash') VALUES ('$name', '$password', '$email', '$hash' )");
if($con === false) {
    echo 'error - ';
    echo mysqli_error($con);
} else {
    echo 'all good';
}