Display every Nth row

from the Artful Common Queries page

Display every Nth row in tbl where id is sequential in MySQL before version 4.1: 
SELECT id
FROM tbl
GROUP BY id 
HAVING MOD(id, N) = 0;
or 
SELECT a.*
FROM tbl a
JOIN tbl b ON a.id = b.id AND MOD(b.id, N ) = 0;
In MySQL 4.1 and later you can also write: 
SELECT *
FROM tbl
WHERE ( id, 0 ) IN ( SELECT id, MOD( id, N ) FROM tbl );
or 
SELECT *
FROM ( SELECT id FROM tbl ) AS tmp
WHERE MOD( tmp.id, N ) = 0;

Last updated 2 Sep 2024