mybatis even table query one2one
1. The association between master and slave can query the table primary key twice
ResultMap association tag map <Property association = "info" column = "user_id"
the javaType = "the UserInfo"
Then obtained from the mapping table corresponding to the select attribute mapper method getUserInfoByUserId
select = "com.gezhi.mapper.UserInfoMapper.getUserInfoByUserId">
</ Association>
From mapper table
<sql id="userInfoSql">
info_id,info_nickname,info_phone,info_email,info_gender,info_address
</sql>
<select id="getUserInfoByUserId" resultMap="userInfoMap"
parameterType="int">
select
<include refid="userInfoSql"></include>
from user_info where user_id=#{id}
</select>
2. left join query table even once
Remove the select attribute, from the added result Map Table
<association property="info" column="user_id"
javaType="UserInfo"
resultMap="com.gezhi.mapper.UserInfoMapper.userInfoMap">
</association>
From the table mapper
<!-- 联合查询users表中的信息,双向关联 -->
<resultMap type="UserInfo" id="userInfoMap">
<id property="infoId" column="info_id" javaType="integer" />
<result property="nickName" column="info_nickname"
javaType="java.lang.String" />
<result property="phone" column="info_phone"
javaType="java.lang.String" />
<result property="Email" column="info_email" javaType="string" />
<result property="gender" column="info_gender"
javaType="string" />
<result property="address" column="info_address"
javaType="java.lang.String" />
<association property="user" column="user_id"
javaType="User" resultMap="com.gezhi.mapper.UserMapper.userResultMap">
</association>
</resultMap>