Re: What is the meaning of the return value from a DBI do statement?

Larry W. Virden schrieb:
> I'm using DBI to interact with ORACLE . I have a number of statements
> - select, insert, update, and delete - that are executed depending on
> the logic.
> 
> When I execute the $handle->do statement, is the return code a simple
In Your code example You do NOT use $handle->do()...

> true or false as to whether the statement worked, or does the value
> mean something more?

It means: "Returns the number of rows affected or undef on error. A return value 
of -1 means the number of rows is not known, not applicable, or not available." 
(http://search.cpan.org/~timb/DBI-1.609/DBI.pm#do). Your example code recognise 
this correctly.

> 
> I'd like to be able to determine how many rows the statement acted
> against.
> 
> For example, in one part of the code, I tried doing this:
> 
>     $drc = $handle->prepare ("DELETE FROM MyTable WHERE EMPNO = ?") or

This must be written as

$oraProdDBH = $handle->prepare ("DELETE FROM MyTable WHERE EMPNO = ?") or

otherwise Your code will never work.

> do {
>         print "DELETE prepare failed - $DBI::errstr\n";
>         next;
>     }
>     $drc = $oraProdDBH->execute ($employee) or do {
>         print "DELETE execute for $employee failed - $DBI::errstr\n";
>         next;
>     }
>     if ($drc != 1) {
>         if ($drc eq '0E0' or $drc == 0) {
>                 print "DELETE from MyTable for EMPNO $employee changed
> 0 rows\n";
>         } else {
>                 print "DELETE from MyTable for EMPNO $employee changed
> $drc rows\n";
>         }
>     }
> 
> thinking that I was logging useful information about the deletion.
> However, it seems like I frequentlly see the "changed 0 rows" message
> coming out at times when I should have seen a row deleted.
> 
> Is this the method of testing to see if, in this case, the DELETE
> deleted any rows, and if so, how many? If not, what would be the way?
> And would this other way handle updates as well?

The problem is that You check the return value of $sth->execute() ...


Greetings

Robert