Hello, Martijn

> > Let's have a table T1 with one field, DATELP : DATE;
> > and fill it with two values, '1.5.2002' and '1.6.2002',
> > for example.
> >
> > Let's make procedure P1, with
> > DATEINPUT : DATE as input parameter, and
> > DATEOUTPUT : DATE as output parameter, and body:
> >
> > BEGIN
> > SELECT FIRST 1 DATELP FROM T1
> > WHERE (DATELP > :DATEINPUT)
> > ORDER BY DATELP
> > INTO :DATEOUTPUT;
> > SUSPEND;
> > END
> >
> > If we execute procedure with DATEINPUT = '1.1.2004',
> > output result is NULL, as expected, because there isn't
> > a date bigger than '1.1.2004' in the table.
>
>It's NULL because variables and (output) parameters are
>initialized with NULL.
>
> > So, let's change the procedure, just add one statement
> > into body:
> >
> > BEGIN
> > DATEOUTPUT = '1.1.2000'; /* <-- */
> > SELECT FIRST 1 DATELP FROM T1
> > WHERE (DATELP > :DATEINPUT)
> > ORDER BY DATELP
> > INTO :DATEOUTPUT;
> > SUSPEND;
> > END
> >
> > Now, if we execute the procedure with the same input value,
> > it returns '1.1.2000' instead NULL.
> > It seems, that select (or INTO clause) do not force
> > value into parameter (dateoutput), if the value is null.
>
>Nope - the output result is alright. There IS NO RESULTSET -
>so there's nothing to put into "dateoutput", therefore, the previous
>value stays in the variable/parameter.

Yes, I got the point.
Thank you, Martijn.

> > And, 3-rd example:
> > Procedure P3, with the same i/o parameters, as above,
> > and with body:
> >
> > BEGIN
> > DATEOUTPUT = '1.1.2000';
> > SELECT DATEOUTPUT FROM P1 ( :DATEINPUT )
> > INTO :DATEOUTPUT;
> > SUSPEND;
> > END
> >
> > If we "hide" select into procedure (P1), returned value
> > is again NULL, as it has to be.
>
>P1 with the "dateoutput = '1.1.2000'" or without it?

Without it - the first variant.
But due to your explanation above,
I understood why the result is null.

Thanks again.


--
Sergey Ganev