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Martin Hope
Lecron
Asked: 2024-08-15 14:25:20 +0000 UTC
  • 6

有 2 个一对多相关的表。

CREATE TABLE main (
    id INTEGER,
    filter_c TEXT
);

INSERT INTO main (id, filter_c) VALUES
(1, 'data1'),
(2, 'data2');

CREATE TABLE feature (
    main_id INTEGER,
    mark_c TEXT
);

INSERT INTO feature (main_id, mark_c) VALUES
(1, 'mark1'),
(1, 'mark1'),
(1, 'mark2'),
(1, null);

注册必要的索引。表的大小分别为7k和2m。预计增长3-4倍。重单位与获取统计数据相关：

SELECT main_id, sum(amount) as total, mark_c as best, max(marked) as goods, sum(marked) - max(marked) as bads
FROM (
    SELECT main_id, mark_c,
        count(*) as amount, --включая Null
        count(mark_c) as marked --исключая Null
    FROM feature
    GROUP BY main_id, mark_c
)
GROUP BY main_id

整个表的执行时间约为 7 秒。但这几乎没有必要。最多main会过滤 10 条记录，您需要从中获取统计数据。预期获取方式

SELECT id, filter_c,
    (SELECT main_id, sum(amount) as total, mark_c as best, max(marked) as goods, sum(marked) - max(marked) as bads
    FROM (
        SELECT main_id, mark_c,
            count(*) as amount, --включая Null
            count(mark_c) as marked --исключая Null
        FROM feature
        WHERE main_id = id --ПРЕФИЛЬТР
        GROUP BY main_id, mark_c
        )
    GROUP BY main_id)
FROM main
WHERE filter_c = 'data1'

但是您不能在这样的子查询中返回多个字段。还有哪些其他方法可以仅收集您需要的记录的统计信息？

sql
Martin Hope
Lecron
Asked: 2020-09-27 00:57:02 +0000 UTC
  • 0

有一个这样的文件结构：

root
|--project1
|    |--__init__.py
|    |--subrunner.py
|    |--proc.py
|--project2
|--projectN
|--runner.py

跑步者.py

from project1.subrunner import foo  

foo()

subrunner.py

此导入版本：

from proc import bar

def foo():
    bar()

允许你运行subrunner，但在启动时runner我们得到一个错误：ModuleNotFoundError: No module named 'proc'.
而这个导入版本：

from .proc import bar

通过点相对，反之亦然。允许你运行runner，但是当你运行时subrunner我们得到一个错误：ModuleNotFoundError: No module named '__main__.proc'; '__main__' is not a package

如何正确导入，使其在启动时runner和启动时都能正常工作subrunner？

python