At 07:53 PM 26/07/2004 +0200, you wrote:

>Hello:
>
>I want to know if there are any special reason
>why Firebird doesn't allow to check for nulls
>in query parameters by doing:
>
> ? IS NULL
>
>It raises the exception:
>
>Dynamic SQL Error.
>SQL error code = -804.
>Data type unknown.
>
>when preparing the command.

Why would you try to do this? Null isn't a value.

What's wrong with

WHERE aValue = ? OR aValue IS NULL

??

/heLen