hibernate 查指定字段报错
查询是这样写的： StringBuffer hql = new StringBuffer("select new Archive (a.id, "
+ "a.releaseDate, " + "a.user, " + "a.attribute, "
+ "a.title, " + "a.keywords, " + "a.description, "
+ "a.updated, " + "a.click, " + "a.picname, " + "a.deleted, "
+ "a.isStatic, "
+ "a.fileName, a.category, a.comment) from Archive a");文章 Archive Bean 构造器是这样的：
public Archive(Integer id, Date releaseDate, User user, String attribute,
String title, String keywords, String description, Date updated,
Integer click, String picname, Integer deleted, char isStatic,
String fileName, Category category, Set<Comment> comment) {
this.id = id;
this.releaseDate = releaseDate;
this.user = user;
this.attribute = attribute;
this.title = title;
this.keywords = keywords;
this.description = description;
this.updated = updated;
this.click = click;
this.picname = picname;
this.deleted = deleted;
this.isStatic = isStatic;
this.fileName = fileName;
this.category = category;
this.comment = comment;
}
其中Set<Comment>是评论，与Comment是双向一对多的关系，我想在查询时将它也查询出来，但总说我的hql有问题，如果去掉Comment类似的关联就对了
我该如何解决这个问题？ --------------------编程问答-------------------- 顶一顶，精神抖擞 --------------------编程问答-------------------- 两个表连起来，把你的关系表也放在from里面 --------------------编程问答--------------------
兄弟，生动点哇。 --------------------编程问答-------------------- 报的原始错误是什么，你贴上来。 --------------------编程问答-------------------- 好。错误信息来也：
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'as col_14_0_ from caobug_archives archive0_ inner join caobug_users user1_ on ar' at line 1 --------------------编程问答-------------------- 学习大虾精神，貌似还未解决 --------------------编程问答-------------------- 这个应该是它生成的SQL语句
Hibernate: select archive0_.id as col_0_0_, archive0_.releaseDate as col_1_0_, archive0_.uid as col_2_0_, archive0_.attribute as col_3_0_, archive0_.title as col_4_0_, archive0_.keywords as col_5_0_, archive0_.description as col_6_0_, archive0_.updated as col_7_0_, archive0_.click as col_8_0_, archive0_.picname as col_9_0_, archive0_.deleted as col_10_0_, archive0_.is_static as col_11_0_, archive0_.file_name as col_12_0_, archive0_.tid as col_13_0_, . as col_14_0_ from caobug_archives archive0_ inner join caobug_users user1_ on archive0_.uid=user1_.id inner join caobug_category category2_ on archive0_.tid=category2_.id inner join caobug_comment comment3_ on archive0_.id=comment3_.id order by archive0_.releaseDate desc limit ? --------------------编程问答--------------------
sql语句出现问题 把sql语句copy出来丢到数据库里运行检查错误 --------------------编程问答-------------------- Hibernate: select archive0_.id as col_0_0_, archive0_.releaseDate as col_1_0_, archive0_.uid as col_2_0_, archive0_.attribute as col_3_0_, archive0_.title as col_4_0_, archive0_.keywords as col_5_0_, archive0_.description as col_6_0_, archive0_.updated as col_7_0_, archive0_.click as col_8_0_, archive0_.picname as col_9_0_, archive0_.deleted as col_10_0_, archive0_.is_static as col_11_0_, archive0_.file_name as col_12_0_, archive0_.tid as col_13_0_, . as col_14_0_ from caobug_archives archive0_ inner join caobug_users user1_ on archive0_.uid=user1_.id inner join caobug_category category2_ on archive0_.tid=category2_.id inner join caobug_comment comment3_ on archive0_.id=comment3_.id order by archive0_.releaseDate desc limit ?
这里就出现问题了，但HQL生成的语句这是这样呢？？ --------------------编程问答-------------------- 你的那个关系型comment不要用，如果你要引用的话也得去关系表里，它本身就是关系，你用hibernate做映射的时候你配置的它的属性应该是对应的关系表，你不能这样单独的引用它，所以你的hql里面不能直接有它，有它也是从关系表引出的
from Archive a inner join comment c on a.comment = c.comment
select里面最好是c.comment
你的java类也需要改 --------------------编程问答-------------------- 你还没了解hibernate的原理啊
既然你配置了关系
那么你查archive出来
然后archive对象里面就已经能直接拿到Comment的信息了
比如说
我查出来的是archive
我直接就能archive.comment
而且这个根据你用get跟load会有延迟加载的区别
根本不用在hql语句里面写上comment
而且你这个hql写的这样我看起来有点蛋疼啊
你唯一定位一条数据
需要这么多字段呢？ --------------------编程问答-------------------- hibernate是一个o/r mapping 框架
他做的就是把表转换成对象了
你直接把查数据当做操作对象就好
你查出来a
a里面不管有B，C,D多少个关联对象
你都能直接点出来
不要再写什么条件去查
不然要你配置关联做什么
hibernate的优势不就在这吗 --------------------编程问答--------------------
谢谢兄弟指教，我现在的需求是不查询某些字段，比如网站首页查询文章是不需要展示查询正文的~ --------------------编程问答--------------------
这样啊 那你根据特定字段查回来的就是数组哦 只写查询那个对象的条件就行了 关联对象不用写条件了 hibernate帮你找的 --------------------编程问答-------------------- Hibernate里可以用SQL语句，不用HQL语句。建议用SQL语句试试
补充：Java , Web 开发
