my $sql = qq{
   insert into customers
   ( id, name )
   values
   ( '$id', '$name' )   -- XXX BUG
};

$dbh->do( $sql );

##</code><code>##

my $id_sql   = $dbh->quote( $id );
my $name_sql = $dbh->quote( $name );

my $sql = qq{
   insert into customers
   ( id, name )
   values
   ( $id_sql, $name_sql )
};

$dbh->do( $sql );

##</code><code>##

my $sql = qq{
   insert into customers
   ( id, name )
   values
   ( ?, ? )
};

$dbh->do( $sql, undef, $id, $name );