Hello all, According to the documentation, it is more efficient to do (I'm paraphrasing):

$sth = $dbh->prepare($sql);
foreach (@ValueList) {
  $sth->execute($_);
}
[download]

than

foreach (@ValueList) {
  $dbh->do("Interpolated sql statement");
}
[download]

So I'm trying to figure out why, in the following example, Code1, which uses the prepare strategy, benchmarks slower than Code2, which uses repeated dos? BTW, in the actual program the @Result array is different for each element of the @Took array, hence the apparent circumlocution.

Thanks in advance, Brian

#!/usr/bin/perl -w

use strict;
use Benchmark qw/:all/;

my $times = shift;

sub UpdateDBIar {
    my ($arsql) = @_;
    use DBI;
    my $dbh = DBI->connect("dbi:mysql:database=SchoolToolsDev;host=loc
+alhost;user=stadmin;password=stadmin") or die "Couldn't connect to da
+tabase $DBI::errstr\n";
    foreach my $sql (@$arsql) {
        $dbh->do($sql) or die "Couldn't execute sql: $sql $dbh->errstr
+";
    }
}

sub UpdateDBIar2 {
    my ($arargs) = @_;
    use DBI;
    my $dbh = DBI->connect("dbi:mysql:database=SchoolToolsDev;host=loc
+alhost;user=stadmin;password=stadmin") or die "Couldn't connect to da
+tabase $DBI::errstr\n";
    foreach my $argset (@$arargs) {
        my $sql = $argset->[0];
        my $artemp = $argset->[1];
        my $sth = $dbh->prepare($sql);
        foreach my $arg (@$artemp) {
            $sth->execute(join ',', @$arg);
        }
    }
}

my $crCode1 = sub {
    my @Result = (10734..10845);
    my @Took = (qw/Baseline Q1 Q2 Q3 Q4/);
   my $arargs;
    foreach my $Took (@Took) {
        my $sql = "UPDATE Tests SET $Took = '1' WHERE ID = ?";
        my $artemp;
        foreach (@Result) {
            push @$artemp, [$_];
        }
        push @$arargs, [$sql, $artemp];
    }
    UpdateDBIar2($arargs);
};

my $crCode2 = sub {
    my @Result = (10734..10845);
    my @Took = (qw/Baseline Q1 Q2 Q3 Q4/);
    my @sqls;
    foreach my $Took (@Took) {
        foreach (@Result) {
            push @sqls, "UPDATE Tests SET $Took = '1' WHERE ID = '$_'"
+;
        }
    }
    UpdateDBIar(\@sqls);
};

timethese ($times, {
            Code1 => $crCode1,
            Code2 => $crCode2,
            }
);
[download]

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