Mybatis 返回值配置理解 - 返回值是浮点数 BigDecimal 或整数 Integer的配置 - 返回指定实体类格式的 List 数组

野性酷女 2024-03-24 20:42 37阅读 0赞

#### 目录 ####

*  前提
 *  1. 返回整形数值
 *  2. 返回值 BigDecimal 浮点数 金额类型
 *  3. 返回指定实体类格式的 List 数组
 *  参考链接

## 前提 ##

Mybatis报错： `A query was run and no Result Maps were found for the Mapped Statement`

> mybatis中的所有查询标签，都必须返回`resultType`或者`resultMap`的值，否则就会报如上错误的，其实仔细看看因为报错原因的意思就好了

## 1. 返回整形数值 ##

`TestMapper.xml` 演示：

<select id="getReturnNum" resultType="java.lang.Integer">
            SELECT COUNT(1)
            FROM test_table
    </select>

Java 调用演示：

@Autowired
    private TestMapper testMapper;
    
    Integer mycount = testMapper.getReturnNum();

## 2. 返回值 BigDecimal 浮点数 金额类型 ##

`TestMapper.xml` 演示：

<select id="getReturnAmount" resultType="java.math.BigDecimal">
            SELECT IFNULL(SUM(mymoney), 0.00)
            FROM test_table
    </select>

Java 调用演示：

@Autowired
    private TestMapper testMapper;
    
    Integer mycount = testMapper.getReturnAmount();

## 3. 返回指定实体类格式的 List 数组 ##

`TestMapper.xml` 演示：

<select id="getReturnList" resultType="com.test.entity.MyEntity">
            SELECT *
            FROM test_table
    </select>

Java 调用演示：

import com.test.entity.MyEntity;
    
    @Autowired
    private TestMapper testMapper;
    
    List<MyEntity> myList = testMapper.getReturnList();

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

## 参考链接 ##

[Mybatis报错： A query was run and no Result Maps were found for the Mapped Statement][Mybatis_ A query was run and no Result Maps were found for the Mapped Statement]

[Mybatis_ A query was run and no Result Maps were found for the Mapped Statement]: https://blog.csdn.net/xiaodexiaoguai/article/details/106956705