From: Michael Dykman
Date: November 17 2009 3:32pm
Subject: Re: Query!
List-Archive: http://lists.mysql.com/mysql/219393
Message-Id: <814b9a820911170732l1f9e24d4h1ec47fa4c1bc3e1a@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

I'm sorry, you are way off here in what this actually does.

mysql_affected_rows is only going to tell you how many rows were
affected by the execution of the last statement made on your current
connection.  It is not an interface to a magic genie maintaining watch
over the state of your entire database.

The only ways you might accomplish anything even remotely like what
you have in mind are:
         have your watcher thread thread make a snapshot of the entire
db and run a diff on every cycle which would be ridiculously expensive
in terms of execution time not to mention locking up database access
pretty good.

OR
        have the external updating process record a log of changes to
a  particular table, then you monitor thread can scan that table for
new entries.


 - michael dykman

On Tue, Nov 17, 2009 at 7:06 AM, Gaurav Nigam (TMP-Japan)
<G.Nigam@stripped> wrote:
> Can somebody please help!
>
> There are two queries -
> 1. How can I detect from my code whether a table has been updated in the =
Database manually (I am firing delete from testtable where SrNo>=3D9; on th=
e Database server) and not from the code itself. I am running this code -
>
> conn =3D mysql_init(NULL);
>
> =A0 =A0 =A0 =A0 =A0 =A0/* Connect to database */
> =A0 =A0 =A0 =A0 =A0 =A0if (!mysql_real_connect(conn, server, user, passwo=
rd, database, 0, NULL, 0)) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0fprintf(stderr, "%s\n", mysql_error(conn));
> =A0 =A0 =A0 =A0 =A0 =A0 =A0exit(1);
> =A0 =A0 =A0 =A0 =A0 =A0}
>
> =A0 =A0 =A0 =A0 =A0 =A0my_ulonglong affect_fields;
> =A0 =A0 =A0 =A0 =A0 =A0while(1)
> =A0 =A0 =A0 =A0 =A0 =A0{
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0affect_fields =3D mysql_af=
fected_rows(conn);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if ((long) affect_fields >=
=3D1)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0{
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0pr=
intf("%ld products updated\n\n", =A0(long) affect_fields);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
> =A0 =A0 =A0 =A0 =A0 =A0}
>
> 2. And if the table is really updated/inserted/deleted for any record the=
n how to check which that record was.
>
> Regards,
> Gaurav.
>



--=20
 - michael dykman
 - mdykman@stripped

"May you live every day of your life."
    Jonathan Swift

Larry's First Law of Language Redesign: Everyone wants the colon.