日期:2014-05-18  浏览次数:20594 次

帮我优化一句sql去除NOT IN语句
SQL code

EXEC('SELECT TOP '+@count+' * FROM [webcontent] WHERE enable=1 AND ID NOT IN(SELECT TOP '+@index+' ID FROM [webcontent] WHERE enable=1 ORDER BY [we_time] DESC) ORDER BY [we_time] DESC');


语句如上,可以正常使用,可是NOT IN对数据查询不好,请高手帮我去除,代换,提高查询速度。

用以上的NOT IN查询 82万条数据时就变得很慢了。
谢谢!

------解决方案--------------------
不知道你是需要升序,还是倒序?

SQL code
exec('SELECT TOP ' + cast(@count - @index as varchar) + ' ID FROM [webcontent] WHERE enable=1 ORDER BY [we_time] desc)'
exec('SELECT TOP ' + cast(@count - @index as varchar) + ' ID FROM [webcontent] WHERE enable=1 ORDER BY [we_time])'

exec('SELECT TOP ' + cast(@count - @index + 1 as varchar) + ' ID FROM [webcontent] WHERE enable=1 ORDER BY [we_time] desc)'
exec('SELECT TOP ' + cast(@count - @index + 1 as varchar) + ' ID FROM [webcontent] WHERE enable=1 ORDER BY [we_time])'

------解决方案--------------------
SQL code

--try:
EXEC('select * from (SELECT TOP '+ltrim(@count)+' * FROM (select top '+ltrim(@index+@count)+' * from webcontent where enable=1 order by we_time desc)a order by we_time)a order by we_time desc')


另外给id,we_time字段加上索引。。

------解决方案--------------------
SQL code
EXEC(
'select 
  * 
 from
 (
   SELECT 
       TOP '+ltrim(@count)+' * 
   FROM 
      (select 
          top '+ltrim(@index+@count)+' * 
       from
          webcontent
        where
          enable=1 
        order by
           we_time desc)a 
 order by we_time)a 
order by we_time desc')

------解决方案--------------------
看你想要表达的意思应该是:查找一个记录集第M条到第N条记录。
你可以用你的语句结合,Exception关键字来实现
SELECT TOP M FROM TABLE WHERE .... ORDER BY ....
EXCEPTION
SELECT TOP N FROM TABLE WHERE .... ORDER BY ....