Adding onto swguy's post:
After querying for a list of where-not-exists, for your own records,
it might be possible to insert all missing ones with something like:
Code:
INSERT INTO products_description (products_id, products_name, products_description, language_id)
SELECT p.products_id, p.products_model, 'description missing, contact our administrator', l.languages_id
FROM products AS p
CROSS JOIN languages AS l
LEFT JOIN products_description AS pd
ON pd.products_id = p.products_id AND pd.language_id = l.languages_id
WHERE pd.products_id IS NULL;
(and then you could search for "administrator" to fix all of those products.)