Write Database for large dataset

I am attempting to limit the number of queires supplied back from the Read Database operator. When I write the code in SQL the LIMIT operator does not seem to be valid. What should I be using? 

SELECT `id_unique`
FROM `retrieved_id`
WHERE `id_count` IS NOT NULL
LIMIT 1000

Rapid Miner is giving me the full database back instead of the first 1k rows.