Mybatis many=@Many的传值问题解决_Java

1. 给子查询传递一个值

@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);

三个表
用户表: user
角色表：role
用户角色关联表：user_role

①主查询，查询得到结果；
将主查询结果里面的id字段赋给③；
③里面的id为子查询的条件，③的id与①主查询里面的数据库字段相对应；
selectbyusernameroleid通过③的coulmn为查询条件。

2. 给子查询传递多个值

@mapper---------------主查询和子查询都要打上注解mapper，才可以映射过去
@select("<script>"
+ "select user_id "
+ "case "
+ "when (#{username} = '' or #{username} is null) "
+ "then null "
+ "else #{username} end as user_name"---------------------核心语句，注意这边是=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是查询返回映射到dto里面的变量，在column里面放置传到查多语句中的参数username，userid
})
list<xxxdto> searchxxx(@param("username") string username);---------传递过去的参数

@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);------对应的参数一定要是mapper

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