Note sql query

select * query the entire table all the fields in such bad writing, because the database along with business development, the field has also increased, to check what time look-up table, we can define sql labels such as:

 <sql id="Base_Column_List">
    id, username, password, email, phone, question, answer, role, create_time, update_time
 </sql>

Then this

  <select id="selectLogin" parameterType="map" resultMap="BaseResultMap">
    SELECT
    // 使用 include 标签重用重用mybatis的代码段
   <include refid="Base_Column_List" />
    from mmall_user
    where username = #{username}
    and password = #{password}
  </select>

updateByPrimaryKeySelective and updateByPrimaryKey difference:

updateByPrimaryKeySelective field judge will then update (if you ignore Null update), if you want to update a field, you can use this method.
updateByPrimaryKey to update you inject all fields

Reproduced in: https: //www.jianshu.com/p/9a241ed8bedd