Question

我有一个名为push_message_info的mysql表，我想过滤然后计算一些结果。获得结果的查询是：

SELECT p.pending, s.success, t.total
FROM 
    (SELECT count(*) AS pending FROM push_message_info WHERE served < total) AS p,
    (SELECT count(*) AS success FROM push_message_info WHERE served = total) AS s,
    (SELECT count(*) AS total FROM push_message_info) AS t
;

事情是我想只计算最新的条目。由于它有一个名为submit_date的日期时间字段，我认为这样的事情会起作用：

SELECT p.pending, s.success, t.total
FROM 
    (SELECT * FROM push_message_info WHERE DATE(submit_date) > '2017-05-14') AS filtered
    (SELECT count(*) AS pending FROM filtered WHERE served < total) AS p,
    (SELECT count(*) AS success FROM filtered WHERE served = total) AS s,
    (SELECT count(*) AS total FROM filtered) AS t
;

但它让我错误：

ERROR 1146（42S02）：表'unifiedpush.filtered'不存在

如何过滤/限制原始表格，以便我可以对该新表格应用其他查询？

Answer 1

您的查询一般不太好。您可以通过一个简单的查询来完成所有这些子查询。

SELECT 
    SUM(CASE WHEN served < total THEN 1 ELSE 0 END) AS pending,
    SUM(CASE WHEN served = total THEN 1 ELSE 0 END) AS served,
    COUNT(*) as total
FROM push_message_info
WHERE DATE(submit_date) > '2017-05-14';

我已将count s（total除外）与SUM(CASE WHEN ... THEN 1 ELSE 0 END)切换为允许您进行条件计数。

Answer 2

好吧，我可以告诉你我是如何完成这样的事情的。尝试：

import pandas as pd

csv_file = pd.read_csv('U:\\INSEE\\Data.csv',sep=';')
csv_file.to_excel('U:\\INSEE\\fichier.xlsx')

这应该能满足你的需要......

Answer 3

查询中的问题是过滤后的别名的范围：从其他子查询中看不到它。

如果你真的想拥有它，你可以创建一个视图：

create view filtered as SELECT * FROM push_message_info WHERE DATE(submit_date) > '2017-05-14';

SELECT p.pending, s.success, t.total
FROM
    (SELECT count(*) AS pending FROM filtered WHERE served < total) AS p,
    (SELECT count(*) AS success FROM filtered WHERE served = total) AS s,
    (SELECT count(*) AS total FROM filtered) AS t;

在MySQL中应用查询之前过滤表

3 个答案: