Hello,
first of all, this is not a support list; next time please use
firebird-support instead.

As per your question...

e> SELECT *
e> FROM DATI
e> where ABBREVIA IN (:param)
e> i'm not able to setting the correct value?

e> :param = 'x','FOL' no good
e> :param = 'x,FOL' no good
e> :param = ''x'',''FOL'' no good
e> and so on......

You have no way to pass two values in a single param. Either use two
params or build your SQL string on the fly.

Ciao
--
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