MyBatis-Plus CRUD之R字决（查询）和D字决（删除）

查询

一般的查询

test

@SpringBootTest
class MybatisPlusFastStartApplicationTests {
    @Autowired
    private UserMapper userMapper;
    @Test
    void selectMethod(){
        List<User> users = userMapper.selectBatchIds(Arrays.asList(1L, 3L, 5L));
        System.out.println(Arrays.toString(users.toArray()));

    }
    @Test
    void selectMethod2(){
        HashMap<String, Object> map = new HashMap<>();//方式二
        map.put("name","mmgg");
        map.put("age",77);
        List<User> users = userMapper.selectByMap(map);
        System.out.println(Arrays.toString(users.toArray()));
    }
 
}
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分页查询

• 需要注入插件
• 创建Configuration类，注入bean

@Configuration
public class MyBatisPlusConfig {
    @Bean
    public MybatisPlusInterceptor paginationInnerInterceptor(){//分页插件
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return interceptor;
    }
}
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test

@SpringBootTest
class MybatisPlusFastStartApplicationTests {
    @Test
    void pagination(){
        /*
        分页构造函数
         参数:
         current – 当前页
         size – 每页显示条数
         */
        Page<User> page = new Page<>(2,5);
                                         //返回Page                              //返回List
        List<User> userList = userMapper.selectPage(page, null).getRecords();
        System.out.println(Arrays.toString(userList.toArray()));
    }
}    
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删除

• 何谓物理删除和逻辑删除

物理删除

• test

@SpringBootTest
class MybatisPlusFastStartApplicationTests {
   @Test
    void deleteTest(){
        userMapper.deleteById(1383720015207952386L);
        //批量删除
        userMapper.deleteBatchIds(Arrays.asList(1383394648605704193L,1383394648605704194L, 1383680218527526914L));

    }
    @Test
    void deleteWithMapTest(){
       Map<String, Object> map = new HashMap<>();
       map.put("name","mmgg");//删除name=mmgg的选手
       userMapper.deleteByMap(map);
    }
}
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逻辑删除

• 数据库创建删除标记位字段
• pojo创建相应字段并在字段上使用注解@TableLogic
• 配置application。yaml

pojo

配置文件

mybatis-plus:
  global-config:
    db-config:
      logic-delete-field: isDeleted  # 全局逻辑删除的实体字段名(since 3.3.0,配置后可以忽略不配置步骤2)
      logic-delete-value: 1 # 逻辑已删除值(默认为 1)
      logic-not-delete-value: 0 # 逻辑未删除值(默认为 0)
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test

@SpringBootTest
class MybatisPlusFastStartApplicationTests {
    @Test
    void logicDelete(){
        userMapper.deleteById(1L);
    }
}
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查询是查不出来的