Question

    var q = (from Comments in db.tblBlogComments where Comments.blogID == this.ID orderby Comments.date descending select new {
        Comments.userID, Comments.comment, Comments.date
    });

这会返回所有关联的记录，我最好如何选择记录＃10到＃20，这样我才不会加载任何冗余数据？

Answer 1

怎么样：

var q = (
from Comments in db.tblBlogComments 
where Comments.blogID == this.ID 
orderby Comments.date descending 
select new { Comments.userID, Comments.comment, Comments.date }).Skip(10).Take(10);

Answer 2

您可以在结果集上使用.Skip()和.Take()方法。例如：

var q = (from Comments in db.tblBlogComments where Comments.blogID == this.ID orderby Comments.date descending select new {
    Comments.userID, Comments.comment, Comments.date
});

然后使用：

int pageSize = 10;
int page = 3;
var currentPage = q.Skip((currentPage - 1) * pageSize).Take(pageSize);

然后

foreach(var item in currentPage)
{
    ...
}

由于Linq使用延迟执行，将在foreach循环期间创建并执行实际查询。所以SQL查询只返回当前页面的记录。

修改：More information about this subject

Answer 3

int start = 10;
int end = 20;
var q = (from Comments in db.tblBlogComments 
            where Comments.blogID == this.ID 
            orderby Comments.date descending 
            select new {
                          Comments.userID, 
                          Comments.comment, 
                          Comments.date
                       }).Skip(start).Take(end - start);

我不确定Skip是否转换为在数据库中执行的SQL，因此效率可能不高。

Linq选择记录范围

3 个答案: