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Re: DBI prepare and function recursion

by gmax (Abbot)
on Oct 07, 2003 at 10:34 UTC ( #297246=note: print w/replies, xml ) Need Help??


in reply to DBI prepare and function recursion

Move the statement handlers outside the recursive function. Then, instead of passing a dbh, you pass the properly initialized statement handlers;

In addition, you should change the fetch method, so you are sure that the recursed sth is not executing a nested operation while still handling the outer one.

This is untested but it should get you on track.

sub rebuild_tree { my $sth1 = shift; my $sth2 = shift; my $dir_ID = shift; my $left = shift; my $right = $left + 1; $sth1->execute($dir_ID) || return $right + 1; my $recs = $sth1->fetchall_arrayref(); for my $row (@$recs) { $right = rebuild_tree($sth1,$sth2, $row->[0], $right); } $sth2->execute($left, $right, $dir_ID); return $right + 1; } my $sql1 = "select ID, name from DIRECTORIES where parent_ID = ?"; my $sth1 = $dbh->prepare($sql1); my $sql2 = "update DIRECTORIES set lft = ?, rght = ? where ID = ?"; my $sth2 = $dbh->prepare($sql2); my ($dir_ID, $left) = (); # whatever you need my $right = rebuild_tree($sth1, $sth2, $dir_ID, $left );

Update
I remember now that have seen this approach before in one of Joe Celko's tricks in this article, which uses stored procedures to update the tree.

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