学生基本信息查询调整

src/main/resources/mapper/student/BaseStudentMapper.xml

@@ -93,7 +93,7 @@
                 and t4.id = #{dto.queryId}
             </if>
         </if>
-        <if test="dto.gradeId == null">
+        <if test="dto.gradeId != null">
             and t4.grade_id = #{dto.gradeId}
         </if>
         <if test="dto.order == null">