Question

How can I select every thrid row from the table?

if a table has

1
2
3
4
5
6
7
8
9

records
it should pick up 3, 6,9 record. regards less what their data is.

Answer 1

Modulo is what you want…

Assuming contiguous values:

SELECT *
FROM Mytable
WHERE [TheColumn] Mod 3 = 0

And with gaps

SELECT *
FROM Mytable
WHERE DCount("TheColumn", "table", "TheColumn <= " & [TheColumn]) Mod 3 = 0

Edit: To exclude every 3rd record, ...Mod 3 <> 0