If you wish to apply paging in MS Acces use this
SELECT *
FROM (
SELECT Top 5 sub.ClientCode
FROM (
SELECT TOP 15 tblClient.ClientCode
FROM tblClient
ORDER BY tblClient.ClientCode
) sub
ORDER BY sub.ClientCode DESC
) subOrdered
ORDER BY subOrdered.ClientCode
Where 15 is the StartPos + PageSize, and 5 is the PageSize.
EDIT to comment:
The error you are receiving, is because you are trying to reference a column name assign in the same level of the query, namely rownumber. If you were to change your query to:
SELECT *
FROM (
SELECT ClientCode,
(SELECT COUNT(c2.ClientCode)
FROM tblClient AS c2
WHERE c2.ClientCode <= c1.ClientCode) AS rownumber
FROM tblClient AS c1
)
WHERE rownumber BETWEEN 0 AND 15
It should not give you an error, but i dont think that this is the paging result you want.