Re: comparing a DATE column with "one minute ago", type warning?
Date: 13 Oct 2008 11:09:19 GMT
joel garry <joel-garry_at_home.com> wrote:
>> > where lastping < (sysdate - interval '1' minute); >> > ^ ^ >> > col 28 col 36 >> >> > Warning(16,28): PLW-07202: bind type would result in conversion >> > away from column type >> > Warning(16,36): PLW-07202: bind type would result in conversion >> > away from column type >> >> I'd say that the warning is bogus and should be ignored. >> >> According tohttp://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_el... >> the difference between DATE and INTERVAL is a DATE, so if lastping is >> a DATE there should be no implicit conversion necessary.
> I'd say you are incorrectly assuming that since the difference is a
> DATE and one of the operands is a DATE, there is no conversion. But
> if you scroll up a bit from where your link points, you see "When you
> pass a timestamp, interval, or numeric value to a built-in function
> that was designed only for the DATE datatype, Oracle implicitly
> converts the non-DATE value to a DATE value..."
Hmm, it would be nice if you could explain that in more detail, because to me it still apears like this:
- The operator "-" is not "designed only for the DATE datatype", so the quotation should not apply in this case, right?
- There should be no conversion necessary because, in this case, the function "-" is used on a DATE and an INTERVAL DAY TO SECOND argument, and the DATE that (according to the documentation) is supposed to result is compared to a DATE column.
Where do I go wrong?
> I'd agree that it
> pointing to sysdate as part of the problem is kind of strange, but
> code rules over docs, especially when coding.
Those are wise words.
Two things feed my doubt here:
- I have frequently encountered wrong warnings from the PL/SQL compiler, for example about "unreachable code" that was happily reached later.
- As has been remarked, there is no warning for "sysdate - 1/1440", yet according to the documentation:
"If one operand is a DATE value or a numeric value ... ... Oracle implicitly converts the other operand to DATE data." So there should be a warning in this case, no?
Laurenz Albe Received on Mon Oct 13 2008 - 06:09:19 CDT