Question:

echo $_POST['IDnum']; $result = pg_prepare($conn, "city_delete", "DELETE FROM lab5.city WHERE lab5.city.id = $1"); $result = pg_execute($conn, "city_delete", array($_POST['IDnum']));

This displays the correct ID number for the row to be deleted and will delete it inside PSQL, but will not delete when implemented inside the PHP? Any ideas?

Try this:

$result = pg_prepare($conn, "city_delete", 'DELETE FROM lab5.city WHERE lab5.city.id = $1');

The double quotes you used make the $1 a PHP variable instead of a string.

See the example for pg_prepare here: <a href="http://php.net/manual/en/function.pg-prepare.php" rel="nofollow">http://php.net/manual/en/function.pg-prepare.php</a>