Question

我有以下查询，我想调整，因为查询需要更多时间来运行。请帮帮我。

select  info_id 
from info_table 
where info_id not in (select info_id 
                      from some_table 
                      where info_id is not null) 
AND  rownum <= 1000 ;

内部查询返回数百万行，因此存在问题。

Answer 1

select info_id
from info_table e
where not exists (select 'x' from some_table where info_id = e.info_id);

这将避免内部排序或合并，应该更快

您甚至可以尝试外连接

select info_id
from info_table e LEFT OUTER JOIN some_table d
ON e.info_id= d.info_id
WHERE d.dept_no is not null;

Answer 2

SELECT info_id
  FROM info_table
  LEFT OUTER JOIN some_table ON info_table.info_id = some_table.info_id
 WHERE some_table.info_id IS NULL

SQL查询调优（子查询）

2 个答案: