diff --git a/project/src/main/resources/mapper/SimulationProjectMapper.xml b/project/src/main/resources/mapper/SimulationProjectMapper.xml
index 04a3d8d4..ff19d1d2 100644
--- a/project/src/main/resources/mapper/SimulationProjectMapper.xml
+++ b/project/src/main/resources/mapper/SimulationProjectMapper.xml
@@ -702,7 +702,7 @@
                     #{disciplineId}
                 </foreach>
                 )
-                or discipline = '' or discipline = null
+                or discipline = '' or discipline is null
             </if>
         </where>
     </select>
diff --git a/project/src/main/resources/mapper/SimulationTaskMapper.xml b/project/src/main/resources/mapper/SimulationTaskMapper.xml
index 1025016f..f8435ad5 100644
--- a/project/src/main/resources/mapper/SimulationTaskMapper.xml
+++ b/project/src/main/resources/mapper/SimulationTaskMapper.xml
@@ -151,7 +151,7 @@
                 #{disciplineId}
             </foreach>
             )
-            or discipline = '' or discipline = null
+            or discipline = '' or discipline is null
         </if>
 
         <if test='req.sortOrder != null and req.sortOrder == "0"'>
@@ -588,7 +588,7 @@
                 #{disciplineId}
             </foreach>
             )
-            or discipline = '' or discipline = null)
+            or discipline = '' or discipline is null)
         </if>
 
 <!--        <if test='req.sortOrder != null and req.sortOrder == "0"'>-->
@@ -704,7 +704,7 @@
                 #{disciplineId}
             </foreach>
             )
-            or discipline = '' or discipline = null)
+            or discipline = '' or discipline is null)
         </if>
 
 <!--        <if test='req.sortOrder != null and req.sortOrder == "0"'>-->