修改is null 条件判定；

src/main/resources/mapper/hmhj/EntrustSampleMapper.xml

@@ -109,7 +109,7 @@
         e.test_side,
         s.supplier,
         s.manufacturer,
-        (case when cr.calc_result != null then (case when cr.calc_result >0 then 1 else 0 end) else null end) "isQualified"
+        (case when cr.calc_result is null then null else (case when cr.calc_result > 0 then 1 else 0 end) end) "isQualified"
         FROM   entrust_sample s
         JOIN entrust e ON s.entrust_id = e.ID
         JOIN (