GROUP BY / COUNT的短查询条件

Question

我在php（替换列）中为cicle生成了这个查询：

select
 count(`a`) as `countAdd`, `a` as `asd`
 from `question`
 where
 (
 (`a` = 1 and ((`v` is not null and `b` not in (1,2)) or (`v` is null and `b` not in (6,7)))
 or
 (`a` = 2 and ((`v` is not null and `b` not in (2,3)) or (`v` is null and `b` not in (8,9)))
 or
 (`a` = 3 and ((`v` is not null and `b` not in (4,5)) or (`v` is null and `b` not in (8,4)))
 or
 (`a` = 4 and ((`v` is not null and `b` not in (4,9)) or (`v` is null and `b` not in (6,2)))
 or
 (`a` = 5 and ((`v` is not null and `b` not in (2,6)) or (`v` is null and `b` not in (3,4)))
 )
 and `deleted_at` is null group by `addresseeId`

在php中

foreach ($a as $v)
    $query .= '(`a` = ? and ((`b` is not null and `c` not in (?)) or (`a` is null `b` not in (?)))';

当我处理更大的数据时，如何避免长时间的查询？

Answer 1

由于这个问题没有那么多非技术背景，我会给你一般性的建议。

有时候获取所需的所有数据然后在php本身进行排序是有意义的。您正在构建的查询可能会变得非常大，因为我会避免在循环中构建查询。

您的问题的另一个可能的解决方案可能是重新设计您的数据库。如果您在某些时候注意到您的查询变得不合适，那么您的数据库设计可能存在一些问题。检查this link以获取数据库设计（感谢@castis）