重新编号一组行

Question

我有一个数据表,如下所示:

# the columns #
url
title
group
id_within_group

http://www.google.com
google
search engine
1

http://www.yahoo.com
yahoo
search engine
2

http://www.bing.com
bing
search engine
3

http://www.facebook.com
facebook
social media
1

http://www.twitter.com
twitter
social media
2

如果我做

select * from table1 where group = "search engine"

我会得到

http://www.google.com
google
search engine
1

http://www.yahoo.com
yahoo
search engine
2

http://www.bing.com
bing
search engine
3

我希望能够删除任何这些行,但不知何故让它重新编号id_within_group.

因此,如果我从上面的3中删除第二个,它应该自动重新编号然后离开我

http://www.google.com
google
search engine
1

http://www.bing.com
bing
search engine
2

这可能吗？

Answer 1

SELECT如果你只需要显示一个连续的整数,我的建议就是这样做.

SELECT   url             ,
         title           ,
         [group]         ,
         id_within_group ,
         ROW_NUMBER() over (partition BY [group] ORDER BY id_within_group) AS sequential_index
FROM     YourTable