@Select({“select * from user where username = #{userName}”}) ①
@Results({
@Result(
property = “id”, column = “id” ②
),
@Result(
property = “roleList”,column=“id”, ③
many = @Many(select = “com.x.dt.mapper.UserMapper.selectByUserNameRoleId”)
)})
List selectByName(String userName);

@Select({"select id from role where id in(select role_id from user_role where user_id=#{userId})"})
List<Role> selectByUserNameRoleId(@Param("userId") String userId);

@Mapper---------------主查詢和子查詢都要打上注解Mapper，才可以映射過去
@Select("<script>"
+ "SELECT user_id "
+ "CASE "
+ "WHEN (#{userName} = '' or #{userName} is null) "
+ "THEN NULL "
+ "ELSE #{userName} END AS user_name"---------------------核心語句，注意這邊是=不是==
+ "FROM sys_user  "
+ "</script>")
@Results({
@Result(column = "{userName=user_name,userId=user_id}", property = "userList", javaType = List.class,
many = @Many(select = "com.dao.xxxDao.searchXxxByName"))--------------------------property是查詢返回映射到DTO里面的變量，在column里面放置傳到查多語句中的參數userName，userId
})
List<XxxDto> searchXxx(@Param("userName") String userName);---------傳遞過去的參數

@Mapper
@Select("<script>"
+ "SELECT * "
+ "FROM sys_detail "
+ "<if test=\"userId!=null \"> "
+ "AND user_id =#{userId} "
+ "</if> "
+ "<if test=\"userName!=null and userName!=\'\' \"> "
+ "AND user_name=#{userName} "
+ "</if> "
+ "</script>")
List<SysDetail> searchXxxByName(Map<String, String> param);------對應的參數一定要是Mapper