Custom Rewrite rules generated dynamically

I have a database table containing a set of music bands. Right now I have a page template ‘viewband’ set up that takes a query string variable ‘id’ and uses it to pull all the info about that band for diaplsy. The URL looks like this:

https://www.mysite.com/viewband/?id=34

I want to create rewrite rules so that the URL can look like this:

https://www.mysite.com/viewband/the-band-name/

I was thinking it could be done using $wp_rewrite. When a new band is added to the database, I could add a new rewrite rule for that band.
Here is my current code that runs when a new band is added to the table:

function addRewriteRule($slug, $id) {
	$rewriteSlug = $slug;
	$rewriteID = $id;
	add_filter('page_rewrite_rules','rewriteBandPages');
	flushRules();
}

function rewriteBandPages($rules) {
	global $rewriteSlug;
	global $rewriteID;
	$newrules = array();
	$newrules['/viewband/('.$rewriteSlug.')$'] = 'id='.$rewriteID;
	return $newrules + $rules;

}

function flushRules() {
	global $wp_rewrite;
	$wp_rewrite->flush_rules();
}

This isn’t doing anything, however. I get a 404 error when using the URL I wanted to create with these functions.

Can anyone help me?