mybatis resultMap solves the problem of inconsistency in attribute and field names

Two solutions to solve the inconsistency of entity class attributes and column names

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The first type (fast execution efficiency, low development efficiency)

1. The attributes in the class are id, name, password
2. The fields in the database are user_id, user_name, user_password
3. In order to allow the data queried by the database to be encapsulated in the User object, aliases can be used
   . This should be written in the mapping file.

<select id="findAll" resultType="com.yixuexi.entity.User">
	select user_id as id,user_name as name,user_password as password from user;
</select>

Summary: This solution is relatively primitive. If there are more fields in the table, the development speed will be very slow.

The second solution (low execution efficiency, fast development speed)

1. Use a configuration of mybatis
2. Configure this directly in the mapping file

<!--id 就是起个名,在使用的时候用这个名就行   type 是哪个实体类-->
<resultMap id="userMap" type="com.yixuexi.entity.User">
	<!--id 是配置主键字段的对应   property 写类中的属性名 column写数据库中对应的字段名-->
	<id property="id" column="user_id"></id>
	<!--result 是非主键字段的对应-->
	<result property="name" column="user_name"></result>
	<result property="password" column="user_password"></result>
</resultMap>

3. Do not use resultType to indicate the result type when querying, use resultMap

<select id="findAll" resultMap="userMap">
	select user_id,user_name,user_password from user
</select>

This can be queried and encapsulated in the entity class.
Notes

• Do not use resultType but use the id of resultMap
• The subtag id in resultMap is used to configure the primary key field
• The subtag result in resultMap is used to configure non-primary key fields

Next article update: JDBC.properties referenced in the main configuration file and some tags of the main configuration file