I am inserting some words into a two-column table with this command:
INSERT IGNORE INTO terms (term) VALUES (\'word1\'), (\'word2\'), (\'word3\');
You get it via SELECT LAST_INSERT_ID(); or via having your framework/MySQL library (in whatever language) call mysql_insert_id().
That won't work. There you have to query the IDs after inserting.
First, to get the id just inserted, you can make something like :
SELECT LAST_INSERT_ID() ;
Care, this will work only after your last INSERT query and it will return the first ID only if you have a multiple insert!
Then, with the IGNORE option, I don't think that it is possible to get the lines that were not inserted. When you make an INSERT IGNORE, you just tell MySQL to ignore the lines that would have to create a duplicate entry.
If you don't put this option, the INSERT will be stopped and you will have the line concerned by the duplication.
Why not just:
SELECT ID
FROM terms
WHERE term IN ('word1', 'word2', 'word3')