Thanks for turning this one over for a moment.

=# SELECT * FROM mlg_addr WHERE mlg_addr_id = '';
ERROR:  invalid input syntax for integer: ""
=# SELECT * FROM mlg_addr WHERE mlg_addr_id IS NULL;
 mlg_addr_id | address1 | address2 | city | state | zipcode5 | zipcode
+4 | country
-------------+----------+----------+------+-------+----------+--------
+--+---------
(0 rows)
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