Works for PG as well

lib/dialects/postgres/query-generator.js

@@ -224,7 +224,7 @@ module.exports = (function() {
         options.attributes = optAttributes.join(', ')
       }
 
-      if(options.where) {
+      if(options.where != undefined) {
         options.where = QueryGenerator.getWhereConditions(options.where)
         query += " WHERE <%= where %>"
       }