capturing mysql errors with backticks

[Mike Wood]

I have a cronned perl script that loads another db's data into my database every morning. The mysql part looks like this:
/usr/local/mysql/bin/mysql -u user -ppassword < load_dbs.sql

It's fairly simple and works most of the time but sometimes it fails. I don't know why it fails and every time I run it manually it works. So I decided to add some error capturing to the mysql call. Essentially I enclosed it in backticks and put the result into a variable.
my $var = `/usr/local/mysql/bin/mysql -u user -ppassword < load_dbs.sql`;

I assumed that the error would show up in the variable (and forces and error with a bad password) but the variable always remains null -- even though when watching it run I can see the error show on the screen. I'm guessing this is because the error I see from mysql is part of it's run and not a return value.

How can I capture what the error is in perl? Or what log can I look in (hours after it happened) to find the error?

Thanks for the help,
Mike