小编dam*_*man的帖子

我有这个简单的Bean类:

public class Book {     

public Book(Map<String, String> attribute) {
    super();
    this.attribute = attribute;
}
//key is isbn, val is author
private Map<String, String> attribute;

public Map<String, String> getAttribute() {
    return attribute;
}
public void setAttribute(Map<String, String> attribute) {
    this.attribute = attribute;
}

}

在我的主要课程中,我向List添加了一些信息:

    Map<String, String> book1Details = new HashMap<String, String>();
    book1Details.put("1234", "author1");
    book1Details.put("5678", "author2");
    Book book1 = new Book(book1Details);

    Map<String, String> book2Details = new HashMap<String, String>();
    book2Details.put("1234", "author2");
    Book book2 = new Book(book2Details);

    List<Book> books = new ArrayList<Book>(); …

我有以下表格:

topic_id(unique)  forum_id   forum_views

1002                1885         5
1003                1893         2
1004                1885         3
1005                1892         6

我怎么能得到这样的输出:(独特的forum_id与上面的论坛总观点)

forum_id    forum_views
1885           8
1893           2
1892           6

任何帮助都是赞赏的.

这就是我想要的:

从table_name中选择distinct forum_id,sum(topic_views)