Mybatis 常用注解及使用案例

绝地灬酷狼 2023-02-11 11:29 10阅读 0赞

**目录**

Mybatis中常用的注解

使用案例

（1）@Select 简单查询

（2）@Insert 简单插入

（3）@Update 简单更新

（4）@Delete 简单删除

（5）@One

（6）@Many

--------------------

## Mybatis中常用的注解 ##

<table style="width:500px;"> 
 <tbody> 
 <tr> 
 <td style="text-align:center;vertical-align:middle;">注解</td> 
 <td style="text-align:center;vertical-align:middle;">目标</td> 
 <td style="text-align:center;vertical-align:middle;">对应的XML标签</td> 
 </tr> 
 <tr> 
 <td>@CacheNamespace</td> 
 <td>类</td> 
 <td>&lt;cache&gt;</td> 
 </tr> 
 <tr> 
 <td>@CacheNamespaceRef</td> 
 <td>类</td> 
 <td>&lt;cacheRef&gt;</td> 
 </tr> 
 <tr> 
 <td>@Results</td> 
 <td>方法</td> 
 <td>&lt;resultMap&gt;</td> 
 </tr> 
 <tr> 
 <td>@Result</td> 
 <td>方法</td> 
 <td> &lt;result&gt; &lt;id&gt;</td> 
 </tr> 
 <tr> 
 <td>@One</td> 
 <td>方法</td> 
 <td>&lt;association&gt;</td> 
 </tr> 
 <tr> 
 <td>@Many&nbsp;&nbsp;</td> 
 <td>方法</td> 
 <td>&lt;collection&gt;</td> 
 </tr> 
 <tr> 
 <td> @Insert @Update @Delete</td> 
 <td>方法</td> 
 <td> &lt;insert&gt; &lt;update&gt; &lt;delete&gt;</td> 
 </tr> 
 <tr> 
 <td> @InsertProvider @UpdateProvider @DeleteProvider @SelectProvider</td> 
 <td>方法</td> 
 <td> &lt;insert&gt; &lt;update&gt; &lt;delete&gt; &lt;select&gt; 允许创建动态SQL</td> 
 </tr> 
 <tr> 
 <td>@Param&nbsp;</td> 
 <td>参数</td> 
 <td>N/A</td> 
 </tr> 
 <tr> 
 <td>@Options&nbsp;</td> 
 <td>方法</td> 
 <td>映射语句的属性</td> 
 </tr> 
 <tr> 
 <td>@select</td> 
 <td>方法</td> 
 <td>&lt;select&gt;</td> 
 </tr> 
 </tbody> 
</table>

## 使用案例 ##

### （1）@Select 简单查询 ###

@Select(" Select * from user ")
 @Results({
 @Result(id = true, column = "id", property = "id"),
 @Result(column = "name", property = "name"),
 @Result(column = "tel", property = "tel"),
 @Result(column = "birth", property = "birth"),
 @Result(column = "address", property = "address")
 })
 List<User> queryAllUser();

### （2）@Insert 简单插入 ###

@Insert(" insert into user(name,sex,age) values(#{name},#{sex},#{age} " )
    int saveUser(User user);

### （3）@Update 简单更新 ###

@Update("update user set name= #{name} ,sex = #{sex},age =#{age} where id = #{id}")
    void updateUserById(User user);

### （4）@Delete 简单删除 ###

@Delete("delete from  user  where id =#{id} ")
    void deleteById(Integer id);

### （5）@One ###

@Select(" select * from user where id = #{id} ")
        @Results(
                value = {
                        @Result(column = "name",property = "name"),
                        @Result(column = "type",property = "type",
                        //one指示我们，查询出来的结果只有一个。
                        one = @One(select="com.xxxx.UserMapper.findTypeById",
                        //及时加载  
                        fetchType = FetchType.EAGER))
                }
        )
        User findUserById(Integer id);

### （6）@Many ###

@Select(" select * from dept")
 @Results({
 @Result(id = true, column = "did", property = "did"),
 @Result(column = "name", property = "name"),
 @Result(column = "address", property = "address"),
 @Result(column = "id",property = "emps",
 //many指示我们，查询出来的结果有很多个
 many = @Many(
 //select = sql语句
 select = "com.xxxx.EmpMapper.findAllEmpByDid",
 //懒加载
 fetchType = FetchType.LAZY))
 })
 List<Dept> findAllDept();

转自：[https://www.cnblogs.com/uiee/p/10778694.html][https_www.cnblogs.com_uiee_p_10778694.html]

表示感谢！！！

@Results、@Result、@ResultMap注解的使用是为了解决实体类名称和数据库名称不一致的问题，使用方法参考如下博客：

参考：  
[https://www.cnblogs.com/voidchar/p/11277572.html][https_www.cnblogs.com_voidchar_p_11277572.html]

[https://www.jianshu.com/p/b5f823ac5355][https_www.jianshu.com_p_b5f823ac5355]

[https_www.cnblogs.com_uiee_p_10778694.html]: https://www.cnblogs.com/uiee/p/10778694.html
[https_www.cnblogs.com_voidchar_p_11277572.html]: https://www.cnblogs.com/voidchar/p/11277572.html
[https_www.jianshu.com_p_b5f823ac5355]: https://www.jianshu.com/p/b5f823ac5355