looking for empty fields

We recently upgraded from version 7.2.3 to 7.3.3 and seem to have some code that has broken. We were doing checks in
variouslocations looking for nulls and/or empty fields. To search for empty fields we said something like <br /><br />
selectcount(am_pk) from arraymeasurement where al_fk is null or al_fk='';<br /><br /> Is this not allowed anymore? All
mycheck with the double ticks are failing. I assume there is a difference in postgres between an empty and null field.
Howcan I check for both in 7.3.3?<br /> Thanks<br /> Jodi<br /><div class="moz-signature">-- <br /></div><div
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_______________________________<br/></span></i><i><span style="font-size: 10pt; ">Jodi L Kanter<br /> BioInformatics
DatabaseAdministrator<br /> University of Virginia<br /> (434) 924-2846<br /><a
href="mailto:jkanter@virginia.edu">jkanter@virginia.edu</a></span></i><span style="font-size: 11pt; font-family: Arial;
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