合并查询后排序的有关问题
日期：2014-05-16 浏览次数：20955 次
合并查询后排序的问题
有两张表，我想把它们查出的结果放到一起，然后再按时间进行排序，最后取前10项，怎末做？
这是查询语句
SELECT PostsId AS id, PostsTitle AS Title,PostsDate AS SendDate, 1 AS Type
FROM BbsPosts
WHERE (PostsUserId = 'admin' AND IsDeleted=False )
UNION ALL
SELECT ReplyId AS id, ReplyTitle AS Title,ReplyDate as SendDate, 2 AS type
FROM BbsReply
WHERE (ReplyUserId = 'admin' AND IsDeleted=False )
可以吧需要的结果都查出来，然后怎么排序和取前10行？
表结构是：
BbsPosts：
PostsId PostsTitle PostsDate ....
---------------------------------
和表
BbsReply：
ReplyId ReplyTitle ReplyDate ....
---------------------------------
想要的结构是：
id Title SendDate Type
-----------------------
只要时间最靠后的10项
------解决方案--------------------
有两张表，我想把它们查出的结果放到一起，然后再按时间进行排序，最后取前10项，怎末做？
这是查询语句
SELECT PostsId AS id, PostsTitle AS Title,PostsDate AS SendDate, 1 AS Type
FROM BbsPosts
WHERE (PostsUserId = 'admin' AND IsDeleted=False )
UNION ALL
SELECT ReplyId AS id, ReplyTitle AS Title,ReplyDate as SendDate, 2 AS type
FROM BbsReply
WHERE (ReplyUserId = 'admin' AND IsDeleted=False )
可以吧需要的结果都查出来，然后怎么排序和取前10行？
表结构是：
BbsPosts：
PostsId PostsTitle PostsDate ....
---------------------------------
和表
BbsReply：
ReplyId ReplyTitle ReplyDate ....
---------------------------------
想要的结构是：
id Title SendDate Type
-----------------------
只要时间最靠后的10项
------解决方案--------------------
- SQL code
select top 10 * from ( SELECT PostsId AS id, PostsTitle AS Title,PostsDate AS SendDate, 1 AS Type FROM BbsPosts WHERE (PostsUserId = 'admin' AND IsDeleted=False ) UNION ALL SELECT ReplyId AS id, ReplyTitle AS Title,ReplyDate as SendDate, 2 AS type FROM BbsReply WHERE (ReplyUserId = 'admin' AND IsDeleted=False ) ) order by SendDate desc
------解决方案--------------------
如果是按 SendDate 排序
select top 10 * from (
SELECT PostsId AS id, PostsTitle AS Title,PostsDate AS SendDate, 1 AS Type
FROM BbsPosts
WHERE (PostsUserId = 'admin' AND IsDeleted=False )
UNION ALL
SELECT ReplyId AS id, ReplyTitle AS Title,ReplyDate as SendDate, 2 AS type
FROM BbsReply
WHERE (ReplyUserId = 'admin' AND IsDeleted=False ) )
order by SendDate desc
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