我的意图是:
按时间 大-->小 排序得到结果集(如果时间相同就按照ID 大-->小 排序)。取出最后20条记录
下面两个方法是测试是正确的。
我想问问这两个写法是否完全一样?第二方法在子查询中加了ArticleId DESC,会有不同吗?? 我担心我的测试用例不够好,问问大家。
SELECT * FROM (SELECT TOP 20 * FROM Article ORDER BY AddTime ASC) T ORDER BY AddTime DESC,ArticleId DESC SELECT * FROM (SELECT TOP 20 * FROM Article ORDER BY AddTime ASC,ArticleId DESC) T ORDER BY AddTime DESC,ArticleId DESC
declare @num as int
select @num = count(*) from authors
set @num = @num - 20declare @sql as varchar(200)
set @sql = 'select * from authors where au_id not in (select top ' + cast(@num as char) + ' au_id from authors)'
exec (@sql)
declare @num as int
select @num = count(*) from authors
set @num = @num - 20declare @sql as varchar(200)
set @sql = 'select * from authors where au_id not in (select top ' + cast(@num as char) + ' au_id from authors)'
exec (@sql)
不一样--------------------
说一下啊,具体点,那里会错??
如果不加那列系统会找最左边的列开始排序 所以必须要加不过应该是asc的排序方法
set @i=select count(*)-20 from Tselect * from T where id not in (select top @i id from T)