mybatis 学习整理

一、查询表中的某个字段

dao/mapper

String getSalt(@Param("userName") String userName);

  
    select salt from com_manager
    where user_name = #{userName,jdbcType=VARCHAR} limit 1
  

二、只取部分值，不定义新DTO

dao/mapper :

List> selectPartBook();

service:

List> map = bookMapper.selectPartBook();

    select book_id, book_name, author from book