SQL语句优化一例 row_number not in or

select [id],[poster],[fid],[title],[editername],[modifytime] from(

select [id],[poster],[fid],[title],[editername],[modifytime], row_number() over

( order by id desc) as row from [news] WITH (NOLOCK) 

 where   path like 'A_B%' and  id not in 

 (select id from [news] where layer=7 or layer=5)) a  

 where row between 1 and 15

 

 上面的查询很慢。如果只执行子查询就很快，但是做 where row between 1 and 15 分页就很慢很慢，原来是因为查询里面用了or，优化成下面的就不超时了

 

 select [id],[poster],[fid],[title],[editername],[modifytime] from(

select [id],[poster],[fid],[title],[editername],[modifytime], row_number() over

( order by id desc) as row from [news] WITH (NOLOCK) 

 where   path like 'A_B%' and  id not in 

 (select id from [news] where layer=7 union select id from [news] where layer=5)) a  

 where row between 1 and 15