Re: Looping with DBI

[gav^]

Here's how I'd do it:

my $sth_news = $dbh->prepare("SELECT id, body FROM news");
$sth_news->execute;
$sth_news->bind_columns(\my $news_id, \my $news_body, \my $comments
while ($sth_news->fetch) {
    my $sth_comments = $dbh->prepare("SELECT COUNT(id) FROM comments W
+HERE id = ?");
    $sth_comments->execute($news_id);
    $sth_comments->bind_columns(\my $comments);
    $sth_comments->fetch;
    print "$news_id, $news_body, $comments";
}

You should look through the DBI docs for information on binding variables, it's bother faster and (in this case) more readable.

gav^

[Kanji]

If you're going to go through the trouble of using bind variables, why not move the second prepare outside the while? That way you avoid needless re-prepareing of the same statement on every iteration of the loop...

my $sth_news = $dbh->prepare("
  SELECT id, body 
  FROM   news
");
$sth_news->execute;
$sth_news->bind_columns(\my $news_id,\my $news_body);

my $sth_comments = $dbh->prepare("
  SELECT COUNT(id) 
  FROM   comments 
  WHERE  id = ?
");

while ($sth_news->fetch) {
    $sth_comments->execute($news_id);
    $sth_comments->bind_columns(\my $comments);
    $sth_comments->fetch;
    print "$news_id, $news_body, $comments";
}

    --k.