04_解决字段名与实体类属性名不相同的冲突

1 准备表和数据

CREATE TABLE orders(

order_id INT PRIMARY KEY AUTO_INCREMENT,

order_no VARCHAR(20),

order_price FLOAT

);

INSERT INTO orders(order_no, order_price) VALUES('aaaa', 23);

INSERT INTO orders(order_no, order_price) VALUES('bbbb', 33);

INSERT INTO orders(order_no, order_price) VALUES('cccc', 22);

[/code]

2 定义实体类：表的字段和实体的属性不一致

public class Order {

private int id;

private String orderNo;

private float price;

}

[/code]

3 解决方法

3.1 通过查询的别名

<!-- 通过查询字段的别名来对应 -->

<select id="getOrder" parameterType="int" resultType="Order">

SELECT order_id id, order_no orderNo, order_price price FROM orders WHERE order_id=#{id}

</select>

[/code]测试

@Test

public void test1(){

SqlSessionFactory factory = MybatisUtils.getFactory();

SqlSession session = factory.openSession();

String statement = "cn.imentors.mybatis.test4.orderMapper.getOrder";

Order order = session.selectOne(statement , 2);

System.out.println(order);

}

[/code]3.2 通过resultMap

<resultMap type="Order" id="getOrder2Map">

<id property="id" column="order_id"/>

<result property="orderNo" column="order_no"/>

<result property="price" column="order_price"/>

</resultMap>

<select id="getOrder2" parameterType="int" resultMap="getOrder2Map">

SELECT * FROM orders WHERE order_id=#{id}

</select>

[/code]resultMap : 封装一些映射关系

id : 专门针对主键

result : 针对一般字段

测试

@Test

public void test2(){

SqlSessionFactory factory = MybatisUtils.getFactory();

SqlSession session = factory.openSession();

String statement =  "cn.imentors.mybatis.test4.orderMapper.getOrder2";

Order order = session.selectOne(statement , 2);

System.out.println(order);

}

[/code]
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