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[英]A single function for select query in a project its execution or loading time is fast or slow
[英]sql query while i am excuting select query its loading for long time its not resulting its only loading
它不会导致其加载
select p.*
from contacts p left outer join
(select articleno, size, count(*) as cnt
from bsd t
group by articleno, size
) bc
on p.articleno = bc.articleno and p.size = bc.size
where coalesce(cnt, 0) < (select count(*)
from contacts p2
where p2.articleno = p.articleno and
p2.size = p.size and
p2.id <= p.id
);
上面的查询有很多子查询,由于这些子查询的处理速度变慢,并且如果数据量增加,它将变得更糟,因此最好选择任何其他方式来获取数据,或者使用EXPLAIN查看问题出在哪里
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