How to Limit # of Rows Returned using Openquery on a Linked Server

Question

I have an AS400 Linked Server, and I'm trying to run some queries and get some sample sets, but I can't figure out how to limit the number of rows returned.

I tried:

SELECT * FROM OPENQUERY(LINKED, 'SELECT * FROM LINKED.APLUS.CUS WHERE CMSUSP != ''S'' LIMIT 100')

and

SELECT * FROM OPENQUERY(LINKED, 'SELECT TOP(100) * FROM LINKED.APLUS.CUS WHERE CMSUSP != ''S'' ')

I know I can add the TOP to the SELECT FROM OPENQUERY, but I'm trying to not have the AS400 return 100k rows when I only need 100.

Answer 1

Based on my experience with an AS400 system, I believe you're looking for FETCH FIRST N ROWS ONLY

SELECT * FROM ... WHERE ... ORDER BY ... FETCH FIRST 100 ROWS ONLY

In your example that would be:

SELECT * FROM OPENQUERY(LINKED, 'SELECT * FROM LINKED.APLUS.CUS WHERE CMSUSP != ''S'' FETCH FIRST 100 ROWS ONLY')

It is recommended to include an ORDER BY to ensure that the results are consistent.

See this question and answer for additional details: How to do SQL select top N ... in AS400