Re: Insert if Update failed without Select

[sam wun]

[EMAIL PROTECTED] wrote:
Please also note hat UPDATE returns the number of records updated. If your 
UPDATE returns 0, you know that the record does not exist, and you might 
want to INSERT instead.
   

There is one situation where the number of records updated will return
0, yet the row exists.  If you update the record with the exact same
information, mySQL will return a count of 0 rows updated.  Yet the row
exists.
 

Hi, how can I find out the return value from update if I execute update 
in perl dbi?
Here is my sample code:
$sql ="update transaction set salesvolume=$salesvol, netsales=$netsales,
                       transtype=\"$transtype\", 
returnreason=\"$returnreason\"
                       where prodcode=\"$prodcode\" and 
custcode=\"$custcode\" and date=$transdate";
$udpate_sql = qq {$sql;};
$sth = $dbh->prepare($update_sql) || die "prepare: $update_sql: 
$DBI::errstr";
$sth->execute || die "Unable to execute query: $dbh->errstr\n";
$sth->finish;
print $sql;

Currently I found somethingn strange with mysql(perhaps with perl dbi as 
well), after setup 1 or 2 test data, I tried to make a change to one of 
the fiield in a table, but after update is completed, I don't see the 
corresponding field in a record is updated by the new value.

If I copy the update statement exactly from the output of the print 
statement ( print $sql), and paste it to the mysql login prompt to 
execute it, the update statement  update the record instantly. I don't 
know what is happening here, why perl dbi does not do what the update 
statement supposed to do? Have I missed a commit statement? but I don't 
have idea how to place a commit statement to perl dbi.

Thanks
Sam
             Brad Eacker ([EMAIL PROTECTED])

 


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