I am hosting a celebration and taking advantage of WordPress to handle the website. There exists a separate table (not Wordpress user table) of participants and I would like for all of them to possess a page on our website:

example.com/user1, example.com/user2, etc.

I have been reading through up about Wordpress_Rewrite but am a little confused concerning how to conditionally redirect when the user is available, otherwise start the standard flow.

Any assist in achieving this is much appreciated, thanks!

Edit:

There's just a single one-off-page that I am attempting to toward. At this time, it's utilized with:

example.com/user?username=user1

I wound up carrying this out by prepending a user's url having a tilde (~). The rewrite code is the following:

// Uncomment only when new rewrites have been made 
//add_filter('init', 'wds_flush');

// Leave uncommented 
add_filter('rewrite_rules_array', 'wds_user_rewrite');
add_filter('query_vars','wds_query_vars');

function wds_flush()
{
     global $wp_rewrite;
     $wp_rewrite->flush_rules();
}
function wds_user_rewrite($rules)
{
        global $wp_rewrite;
        $newRule = array(
                '^~(.+)$' => 'index.php?pagename=user&uid=$matches[1]&act=show',
        );
        $newRules = $newRule + $rules;

        return $newRules;
}
function wds_query_vars($vars)
{
        array_push($vars, 'uid');
        array_push($vars, 'act');
        return $vars;
}

Basically understood your condition, you are going to produce a page for every user, so within the permalink structure add tag %postname%, and perhaps install no-category base wordpress plugin.

See if the .htaccess it's produced using the configuration that wordpress write for your structure, when not you can easily copy.