Linq查询2个表按日期排序

本文关键字：日期 排序 查询 2个 Linq | 更新日期: 2023-09-27 18:16:27

这里描述两个表

注释表

ID           Comment Id     OrderDate                                              
---         ----------    --------------------
1           1              2003-10-13 08:00:00
2           2              2003-10-12 10:00:00
3           1              2003-10-10 12:00:00

共享表

ID           Share Id     OrderDate                                              
---         ----------    --------------------
1           1              2003-10-11 08:00:00
2           2              2003-10-15 10:00:00
2           2              2003-10-12 10:00:00

现在，我想从两个表中获取列表日期顺序。

意味着输出将是

ID       OrderDate                                              
---   -------------------
3     2003-10-10 12:00:00(Comment)
1     2003-10-11 08:00:00(Share)
3     2003-10-16 12:00:00(Comment)

我们如何生成Linq查询？？

Linq查询2个表按日期排序

public class ShareEntry
{
    public DateTime Date;
    public int ID;
    public int shareID;
}
public class CommentEntry
{
    public DateTime Date;
    public int ID;
    public int commentID;
}

通过如上所述设置类，LINQ查询应该如下所示：

    IEnumerable<ShareEntry> share = new List<ShareEntry>();
    IEnumerable<CommentEntry> comment = new List<CommentEntry>();
    var output = share
        .Select(x => new
    {
        id = x.ID,
        date = x.Date,
        type = "share"
    })
        .Concat(comment.
            Select(x => new
            {
                id = x.ID,
                date = x.Date,
                type = "comment"
            }))
         .OrderByDescending(x => x.date).Take(10);

根据您的备注，您可以尝试以下查询-

SELECT distinct id, orderdate FROM 
(
SELECT id, orderdate FROM `comment` 
UNION ALL 
SELECT id, orderdate FROM `share` 
) a 
ORDER BY a.orderdate DESC 
LIMIT 10;
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