SQL variable mapping with 'IN'

I have the following SQL statement:

SELECT * FROM

WHERE in ('value_1','value_2',....,'value_n')

and n is variable.

I tried to replace this statement by  SELECT * FROM

WHERE in (?) and use for the sql parameter mapping variable

a string like 'value_1,'value_2','value_3' generated via a custom manipulator without any success.

Do you have any idea to solve my issue?

Thank yopu for your help,

Claude.