Castle学习系列(七)---ActiveRecord HQL介绍

来源：互联网发布：手机打不开数据流量编辑：程序博客网时间：2024/05/19 15:41

ActiveRecord 中HQL也就是NHibernate中的HQL,可用来查询实体。

简单的HQL写法如下：

public static Post[] GetPosts(int id){     SimpleQuery<Post> q = new SimpleQuery<Post>(@"from Post p where p.OwnerBlog.id = ?", id);     return q.Execute();}public static int[] GetPostIdsFromInterval(int start, int end){     SimpleQuery<int> q = new SimpleQuery<int>(typeof(Post), @"select p.Id from Post p where p.Id between :start and :end");     q.SetParameter("start", start);     q.SetParameter("end", end);     return q.Execute();}public int CurrentPostMax(){     ScalarQuery<int> q = new ScalarQuery<int>(typeof(Post), @"select max(p.Id) from Post p where p.OwnerBlog = ?", this);     return q.Execute();}

其中SimpleQuery为简单的查询类，而ScalarQuery为简单的查询单个字段值的类。当然ActiveRecord可用NHibernate的查询方法，代码如下：

public static Post[] GetPostsFromAuthor(String author){     return (Post[])Execute     (         delegate(ISession session, object instance)         {              IQuery query = session.CreateQuery("from Post p where p.OwnerBlog.Name = :author");              query.SetString("author", (String)instance);              IList results = query.List();              Post[] posts = new Post[results.Count];              results.CopyTo(posts, 0);              return posts;         },          author     );}

要了解HQL更多知识，请参考NHibernate官方文档。

0 0