If I understand correctly, you want two dropdown boxes. The first dropdown box will contain all your tables, and the other will contain the rows from the table you selected.
I got a demo working locally. As long as you know the table you're selecting will have the two fields you wanted, "num, title", you should get a working dropdown or you will get a mysql error when selecting that table.
The solution I came up with is this,
I created a field with type "list". The field label and name can be whatever you want. I selected "pulldown" for Display As. List Options was the advanced MySQL Query option.
I used your same query for displaying the table names.
SELECT REPLACE(TABLE_NAME, '<?php echo $TABLE_PREFIX;?>', '') FROM information_schema.`TABLES` where TABLE_SCHEMA = '<?php echo $GLOBALS['SETTINGS']['mysql']['database'];?>' AND TABLE_NAME like '<?php echo $TABLE_PREFIX;?>_%' ORDER BY TABLE_NAME
For Input Validation, I selected the checkbox for "User may not leave field blank".
The second field I created was also of type "list" and it was a pulldown. Using the advanced list options query, I used the following code
<?php
if($ESCAPED_FILTER_VALUE): ?>
SELECT num, title FROM <?php echo $TABLE_PREFIX.$ESCAPED_FILTER_VALUE; ?>
<?php
else:
?>
SELECT "Please select value in field above...";
<?php
endif;
?>
In the Advanced Filter dropdown, I selected the first field so it refreshes upon the first dropdown list being changed. Let me know if this make sense or if you have any other questions.
Carl
PHP Programmer
interactivetools.com