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CREATE SCHEMA IF NOT EXISTS pwc158;
/*
testdb=> select * from pwc158.add_primes( 100 );
add_primes
------------
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*/
CREATE OR REPLACE FUNCTION
pwc158.add_primes( int )
RETURNS SETOF int
AS $CODE$
# function to test if a number is prime
my $is_prime = sub {
my ($value) = @_;
for my $i ( 2 .. $value - 1 ) {
return 0 if ( $value % $i == 0 );
}
return 1;
};
# disassemble a number into its digits and sum them
my $sum_digits = sub {
my ($value) = @_;
my @digits = split //, $value;
my $sum = 0;
$sum += $_ for ( @digits );
return $sum;
};
for my $i ( 1 .. $_[0] ) {
return_next( $i ) if ( $is_prime->( $i )
&& $is_prime->( $sum_digits->( $i ) ) );
}
return undef;
$CODE$
LANGUAGE plperl;
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