MySQL + PHP: select multiple rows on a join, then update those rows/insert new ones

I want to do the following:

1. Select multiple rows on an INNER JOIN between two tables.
2. Using the primary keys of the returned rows, either:
   1. Update those rows, or
   2. Insert rows into a different table with the returned primary key as a foreign key.
3. In PHP, echo the results of step #1 out, ideally with results of #2 included (to be consumed by a client).

I've written the join, but not much else. I tried using开发者_如何学JAVA a user-defined variable to store the primary keys from step #1 to use in step #2, but as I understand it user-defined variables are single-valued, and my SELECT can return multiple rows. Is there a way to do this in a single MySQL transaction? If not, is there a way to do this with some modicum of efficiency?

Update: Here are the schemas of the tables I'm concerned with (names changed, 'natch):

CREATE TABLE IF NOT EXISTS `widgets` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`author` varchar(75) COLLATE utf8_unicode_ci NOT NULL,
`text` varchar(500) COLLATE utf8_unicode_ci NOT NULL,
`created` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated` timestamp 
          NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
);

CREATE TABLE IF NOT EXISTS `downloads` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`widget_id` int(11) unsigned NOT NULL,
`lat` float NOT NULL,
`lon` float NOT NULL,
`date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
);

I'm currently doing a join to get all widgets paired with their downloads. Assuming $author and $batchSize are php vars:

SELECT w.id, w.author, w.text, w.created, d.lat, d.lon, d.date
FROM widgets AS w
INNER JOIN downloads AS d
ON w.id = d.widget_id
WHERE w.author NOT LIKE '$author'
ORDER BY w.updated ASC
LIMIT $batchSize;

Ideally my query would get a bunch of widgets, update their updated field OR insert a new download referencing that widget (I'd love to see answers for both approaches, haven't decided on one yet), and then allow the joined widgets and downloads to be echoed. Bonus points if the new inserted download or updated widgets are included in the echo.

Since you asked if you can do this in a single Mysql transaction I'll mention cursors. Cursors will allow you to do a select and loop through each row and do the insert or anything else you want all within the db. So you could create a stored procedure that does all the logic behind the scenes that you can call via php.

Based on your update I wanted to mention that you can have the stored procedure return the new recordset or an I'd, anything you want. For more info on creating stored procedures that return a recordset with php you can check out this post: http://www.joeyrivera.com/2009/using-mysql-stored-procedure-inout-and-recordset-w-php/