Re^2: DBI disconnect database errors

[Anonymous Monk]

I got this code from Paul, the author of Perl and MySQL for the web...

I did scan the DBI module documentation, and do see the finish calls are different than what I do...

However, I am not reading from the database while it is connected, I store the data in a hashref:

$sth = $dbh->prepare(qq{select * from `table`});
$sth->execute();
my $_somevar = $sth->fetchrow_hashref();
$sth->finish();

or:

$sth = $dbh->prepare(qq{select * from `table`});
$sth->execute();
while(my $_somevar = $sth->fetchrow_hashref()) {
my $_someid = $_somvar->{primarykeyfield};
$sth2 = $dbh->prepare(qq{select * from `table1` where `primarykeyfield
+` = ?});
$sth2->execute($_someid);
$_thisvar = $sth2->fetchrow_hashref();
$sth2->finish();
# now I have data from table in $_somvar
# and data from table1 in $_thisvar
}
$sth->finish();

So, I call finish on them after I'm done reading from there, but not before. That way I don't leave any connections open, is that not correct?

Thanks,
Rich

[mje]

If you want to track down which handles DBI is warning about see visit_handles which would allow you to loop through them and see which are Active and what SQL they are running.

[EvanCarroll]

OK, being able to look at that code, I wold explicitly NOT to do that. I would not explicitly prepare something for a single select, use selectrow_hashref instead, and put in the sql an explicit `LIMIT 1`. Also, using '*' should be reserved, when you want all the rows in the table. This should hold true if one of those rows is a 50 meg block of text.

Also, in your second example you could just as well do that in one query right? Through a join. This saves work on the DB.

$dbh->selectrow_hashref(
    'SELECT t1.* FROM table AS t0'
    . ' JOIN table1 AS t1'
    . ' USING ( primarykeyfield )'
);

Or, if you wanted precisely the same as above, which will render the row from table1 random because the lack of a sort order on table, you can still do that in one statement

$dbh->selectrow_hashref(
    'SELECT t1.* FROM table AS t0'
    . ' WHERE t1.primarykeyfield IN ( SELECT primarykeyfield FROm tabl
+e LIMIT 1 )
);

[Anonymous Monk]

Thanks for that...

I normally just use all the data in both, if I only need info from one table, I do it like this:

# I need the members information for their profile update...
#$_un carries the username they are logged in as:
$sth = $dbh->selectrow_array(qq{select * from `members` where `USERNAM
+E` = ? LIMIT 1});
$sth->execute($_un);
my $_mbrInfo = $sth->fetchrow_hashref();
$sth->finish();
# then go build the html page and form for them to update their profil
+e, prepopulating the data that is already in their

That is how I get their data, however, if I need multiple tables of information, since I store data in multiple tables, I get each of them:

$sth = $dbh->selectrow_array(qq{select * from `members` where `USERNAM
+E` = ? LIMIT 1});
$sth->execute($_un);
my $_mbrInfo = $sth->fetchrow_hashref();
$sth->finish();
# Got member record, now get their billing address:

$sth = $dbh->prepare(qq{select * from `shippingAddresses` where `mid` 
+= ?});
$sth->execute($_mbrInfo->{mid});
my $_addy = $sth->fetchrow_hashref();
$sth->finish();

That is how I get all the info I need, I don't usually get all the fields if I only need a few... If I only need one or two fields I do it this way:

# Get Members Id, Name, Phone, Email:
my($_mbrId,$_mbrName,$_mbrPhone,$_mbrEmail) = $dbh->selectrow_array(qq
+{select `mid`,`name`,`phone`,`email` from `members` where `USERNAME` 
+= ?}, undef, $_un);

Or if I need data only out of another table, but it is based on the members id, and I only have the useranme, I do it like this:

# Get address:
$sth = $dbh->selectrow_array(qq{select * from `shippingAddresses` wher
+e `Id` = (select `mid` from `members` where `USERNAME` = ?)});
$sth->execute($_un);
my $_addy = $sth->fetchrow_hashref();
$sth->finish();

That is how I would get just the fields I need... Since usernames are unique, I don't need to put a limit of 1 on it since there should only be one matching record.

That is how I handle those in my programming.

I am always open to new ideas though. I am currently learning Ajax to make some of the things I do much better, I am loving what I am learning! That is a GREAT language.

Thanks,
Rich