I'm writing a script using a MySQL database. I'm running an update query like this: 
$rows_affected = $dbh->do("UPDATE meters SET description=? WHERE name=
+?", undef, $info, $meter);

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Sometimes this query is issued with $info equal to the value already stored in that description field. The strange part is that $rows_affected is getting set to 1 even if $info is exactly the same as the existing value! I logged into the database manually and ran the query, which returned: 

Query OK, 0 rows affected (0.00 sec)
Rows matched: 1  Changed: 0  Warnings: 0

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MySQL and Perl for the Web (p.37, footnote) says that "affected by" means "changed", and that do() should indeed return 0 in this case, unless I have ";mysql_client_found_rows=1" set, which I do not.

Guesses? Clues? Answers? Berating? I wish I had more information to provide about the problem...

Many thanks,
LassiLantar

Update: Fixed it, as per suggestion, by making the WHERE clause read  ...WHERE name=? AND description=?", undef, $info, $meter, $info... Which resulted in return values of 0E0. Anyone know why MySQL or DBI is refusing to return just plain 0 in this case, and why it's returning 1 without the extra check?

In reply to Odd "rows affected" values using DBI on MySQL by LassiLantar

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