diff --git a/yudao-framework/yudao-common/src/main/java/cn/iocoder/yudao/framework/common/util/date/LocalDateTimeUtils.java b/yudao-framework/yudao-common/src/main/java/cn/iocoder/yudao/framework/common/util/date/LocalDateTimeUtils.java
index 7af32ea82..a29d5fb2e 100644
--- a/yudao-framework/yudao-common/src/main/java/cn/iocoder/yudao/framework/common/util/date/LocalDateTimeUtils.java
+++ b/yudao-framework/yudao-common/src/main/java/cn/iocoder/yudao/framework/common/util/date/LocalDateTimeUtils.java
@@ -12,6 +12,11 @@ import java.time.LocalDateTime;
  */
 public class LocalDateTimeUtils {
 
+    /**
+     * 空的 LocalDateTime 对象，主要用于 DB 唯一索引的默认值
+     */
+    public static LocalDateTime EMPTY = buildTime(1970, 1, 1);
+
     public static LocalDateTime addTime(Duration duration) {
         return LocalDateTime.now().plus(duration);
     }
diff --git a/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/dal/mysql/dict/DictTypeMapper.java b/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/dal/mysql/dict/DictTypeMapper.java
index 31abfc8f6..261f18cc4 100644
--- a/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/dal/mysql/dict/DictTypeMapper.java
+++ b/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/dal/mysql/dict/DictTypeMapper.java
@@ -5,9 +5,7 @@ import cn.iocoder.yudao.framework.mybatis.core.mapper.BaseMapperX;
 import cn.iocoder.yudao.framework.mybatis.core.query.LambdaQueryWrapperX;
 import cn.iocoder.yudao.module.system.controller.admin.dict.vo.type.DictTypeExportReqVO;
 import cn.iocoder.yudao.module.system.controller.admin.dict.vo.type.DictTypePageReqVO;
-import cn.iocoder.yudao.module.system.dal.dataobject.dict.DictDataDO;
 import cn.iocoder.yudao.module.system.dal.dataobject.dict.DictTypeDO;
-import org.apache.ibatis.annotations.Delete;
 import org.apache.ibatis.annotations.Mapper;
 import org.apache.ibatis.annotations.Param;
 import org.apache.ibatis.annotations.Update;
@@ -43,10 +41,8 @@ public interface DictTypeMapper extends BaseMapperX<DictTypeDO> {
         return selectOne(DictTypeDO::getName, name);
     }
 
-    @Update("UPDATE system_dict_type SET DELETED = 1,DELETED_TIME=#{deletedTime} WHERE id = #{id}")
     int deleteById(@Param("id") Long id, @Param("deletedTime") LocalDateTime deletedTime);
 
-    default int deleteById(Long id) {
-        return deleteById(id, LocalDateTime.now());
-    }
+    @Update("UPDATE system_dict_type SET deleted = 1, deleted_time = #{deletedTime} WHERE id = #{id}")
+    void updateToDelete(@Param("id") Long id, @Param("deletedTime") LocalDateTime deletedTime);
 }
diff --git a/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/service/dict/DictTypeServiceImpl.java b/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/service/dict/DictTypeServiceImpl.java
index af698a2b0..07fcf40f3 100644
--- a/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/service/dict/DictTypeServiceImpl.java
+++ b/yudao-module-system/yudao-module-system-biz/src/main/java/cn/iocoder/yudao/module/system/service/dict/DictTypeServiceImpl.java
@@ -2,6 +2,7 @@ package cn.iocoder.yudao.module.system.service.dict;
 
 import cn.hutool.core.util.StrUtil;
 import cn.iocoder.yudao.framework.common.pojo.PageResult;
+import cn.iocoder.yudao.framework.common.util.date.LocalDateTimeUtils;
 import cn.iocoder.yudao.module.system.controller.admin.dict.vo.type.DictTypeCreateReqVO;
 import cn.iocoder.yudao.module.system.controller.admin.dict.vo.type.DictTypeExportReqVO;
 import cn.iocoder.yudao.module.system.controller.admin.dict.vo.type.DictTypePageReqVO;
@@ -58,7 +59,8 @@ public class DictTypeServiceImpl implements DictTypeService {
         // 校验正确性
         checkCreateOrUpdate(null, reqVO.getName(), reqVO.getType());
         // 插入字典类型
-        DictTypeDO dictType = DictTypeConvert.INSTANCE.convert(reqVO);
+        DictTypeDO dictType = DictTypeConvert.INSTANCE.convert(reqVO)
+                .setDeletedTime(LocalDateTimeUtils.EMPTY); // 唯一索引，避免 null 值
         dictTypeMapper.insert(dictType);
         return dictType.getId();
     }
@@ -81,7 +83,7 @@ public class DictTypeServiceImpl implements DictTypeService {
             throw exception(DICT_TYPE_HAS_CHILDREN);
         }
         // 删除字典类型
-        dictTypeMapper.deleteById(id);
+        dictTypeMapper.updateToDelete(id, LocalDateTime.now());
     }
 
     @Override
diff --git a/yudao-module-system/yudao-module-system-biz/src/test/resources/sql/create_tables.sql b/yudao-module-system/yudao-module-system-biz/src/test/resources/sql/create_tables.sql
index 56fc42704..7590e57a3 100644
--- a/yudao-module-system/yudao-module-system-biz/src/test/resources/sql/create_tables.sql
+++ b/yudao-module-system/yudao-module-system-biz/src/test/resources/sql/create_tables.sql
@@ -111,6 +111,7 @@ CREATE TABLE IF NOT EXISTS "system_dict_type" (
     "updater" varchar(64) DEFAULT '',
     "update_time" timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
     "deleted" bit NOT NULL DEFAULT FALSE,
+    "deleted_time" timestamp NOT NULL,
     PRIMARY KEY ("id")
 ) COMMENT '字典类型表';