Hi,
On Jun 21, 2006, at 12:24 PM, Kevin Old wrote:
On 6/21/06, Barry <[EMAIL PROTECTED]> wrote:
Kevin Old schrieb:
> Hello everyone,
>
> I had a horrible thing happen to me this morning and wanted to
make it
> known to the community.
>
> I needed to delete a record from a very large table (yes, it was
> backed up) and like the cli interface of mysql. I ran this query:
>
> delete from tablename where id - 12345;
>
> Notice that I accidentally hit the dash (-) instead of the equal
(=).
> It proved to be disasterous as it deleted all the records from that
> table.
>
> Lucky for me I had a backup from last night and not too many
records
> were added since then and I was able to restore.
>
> For the record, I am aware of the "select before delete" method,
but
> didn't use it in this one instance and it meant a few hours
restoring
> data.
>
> Just wanted to throw this out and see if others had possible
solutions
> for working with the mysql cli interface for maybe setting up
"rules"
> for it to cancel a query if it contains a certain character
(like the
> dash). Fat chance there is, but I thought I'd ask.
>
> Hope this helps someone,
> Kevin
On this one use LIMIT.
If you want to delete specific rows alway use LIMIT.
even if you f**k up you "just" have deleted one row.
If you are luck it is an old one and easy restoreable.
Hi Barry,
So if I understand you correctly, I'd do the following:
delete from tablename where id - 12345 limit 1;
Is that correct?
That still will delete one row, so you still might need a backup to
get back that row.
Another option you might want to look into is using the --safe-
updates option to the command line client. This will prevent you
from doing DELETEs and UPDATEs that don't use an index properly. For
example, in your case deleting the entire table would have been
prevented, whereas the correct id = 12345 would be allowed (assuming
id is the PK or index). I generally always use that option on a
production machine.
It does a few other things as well (LIMIT 1000, max_join_size), so
make sure you check it out before using it. It used to be called --i-
am-a-dummy mode (that option works too), so you might see it referred
to as that in some places.
http://dev.mysql.com/doc/refman/5.0/en/safe-updates.html
Regards,
Harrison
--
Harrison C. Fisk, Trainer and Consultant
MySQL AB, www.mysql.com
Get a jumpstart on MySQL Cluster -- http://www.mysql.com/consulting/
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