Mybatis中,當實體類中的屬性名和表中的字段名不一樣 ，怎么辦 ？

方法一：寫SQL語句時起別名

	<select id="getEmployeeById" resultType="com.atguigu.mybatis.entities.Employee">
		select id,first_name firstName,email,salary,dept_id deptID from employees where id = #{id}
	</select>

方法二：在MyBatis的全局配置文件中開啟駝峰命名規則

mapUnderscoreToCamelCase：true/false 
<!--是否啟用下划線與駝峰式命名規則的映射（如first_name => firstName）-->

<configuration>  
    <settings>  
        <setting name="mapUnderscoreToCamelCase" value="true" />  
    </settings>  
</configuration>

方法三：在Mapper映射文件中使用resultMap來自定義映射規則

	<select id="getEmployeeById" resultMap="myMap">
		select * from employees where id = #{id}
	</select>
	
	<!-- 自定義高級映射 -->
    <resultMap type="com.atguigu.mybatis.entities.Employee" id="myMap">
    	<!-- 映射主鍵 -->
    	<id column="id" property="id"/>
    	<!-- 映射其他列 -->
    	<result column="last_name" property="lastName"/>
    	<result column="email" property="email"/>
    	<result column="salary" property="salary"/>
    	<result column="dept_id" property="deptId"/>
    </resultMap>