At 8:06 PM -0700 2000-06-23, Mike Wexler wrote:
>Paul DuBois wrote:
>>
>> At 6:47 PM -0700 2000-06-23, Mike Wexler wrote:
>> >I just looked up this old thread because I am having a problem with some
>> >old code.
>> >
>> >The basic problem is that I would like to update a record, but if it
>> >doesn't exist I'd like to create it. Back when I was new at SQL I
>> >thought
>> >
>> >$dbh->do(<<EOF);
>> >REPLACE INTO table SET field1='value', uniqueKey='uniqueVal'
>> >EOF
>> >
>> >would do the job nicely. It didn't take make too long to figure out that
>> >this would cause field2 to get erased if the record already existed.
>> >
>> >So the next attempt was
>> >
>> >$sth = $dbh->prepare(<<EOF);
>> >UPDATE table SET field1='value' WHERE uniqueKey='uniqueVal'
>> >EOF
>> >$sth->execute();
>> >
>> >if ($sth->rows == 0) {
>> > $dbh->do(<<EOF);
>> >INSERT INTO table SET field1='value', uniqueKey='uniqueVal'
>> >EOF
>> >}
>> >
>> >But alas if field1 is already equal to 'value' then $sth->rows is equal
>> >to zero and INSERT fails. Of course I check the result of the insert and
>>
>> Don't use $sth->rows to determine whether or not the statement
>> failed. Check the return value of $sth->execute(). If it's undef,
>> the statement failed.
>
>Will execute return undef if the WHERE clause matches no items?
No, because that is not an error, just like it's not an error for a
SELECT to return no rows. It's just an empty result.
--
Paul DuBois, paul@stripped
