I don't see this as an optimization so much as a style question. As others have mentioned, the query building speed is unlikely to matter. I'd prefer this: 
my @FIELDS = qw( field1 field2 field3 );
my @PLACEHOLDERS = ('?') x @FIELD;
my $sql = do {
     local $" = ',';
     "INSERT (@FIELDS) INTO foo VALUES (@PLACEHOLDERS)";
};

[download]
WRT optimization, since you're using a closure to keep a constant list of field names inside of, what's the point of rebuilding the SQL for every query? 
{
    my $SQL;

    BEGIN {
        my @FIELDS = qw( field1 field2 field3 );
        my @PLACEHOLDERS = ('?') x @FIELD;
        local $" = ',';
        $SQL = "INSERT (@FIELDS) INTO foo VALUES (@PLACEHOLDERS)";
    }

    sub run_insert {
        my $dbh = shift || return;
        my $sth = $dbh->prepare($SQL);
        $sth->execute(@_);
        $sth->finish;
    }
}

[download]

Makeshifts last the longest.

In reply to Re: Fast Building of SQL Statements by Aristotle
in thread Fast Building of SQL Statements by hardburn

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