将多个sql语句组合成列答案

【问题标题】：Combining multiple sql statements into columns将多个sql语句组合成列
【发布时间】：2014-01-07 21:14:47
【问题描述】：

我对 SQL 很陌生，我正在运行类似的东西来提取一些数据。但目前我一次运行一个语句并将它们复制到 excel 中。有没有办法将所有这些一起运行？每个语句的级别相同，但 count(ID) 会不同。也可能有些日子一个级别没有任何数据。

select 
    count(ID), level 
from table1 
where createat >= "2013-11-22 00:00:00" and createat <= "2013-11-22 23:59:59" 
group by level;

select 
    count(ID), level 
from table1 
where createat >="2013-11-23 00:00:00" and createat <= "2013-11-23 23:59:59" 
group by level;

select 
    count(ID), level 
from table1 
where createat >= "2013-11-24 00:00:00" and createat <= "2013-11-24 23:59:59" 
group by level;

感谢您的帮助！我希望更多地了解如何编写这些。

【问题讨论】：

1) 提供您使用的数据库类型 2) 使用日期函数从日期列中提取月份中的哪一天，并使用它来简化您的查询和按天分组，如果这是什么你想要

标签： sql select count group-by sum

【解决方案1】：

SELECT
  level,
  COUNT(CASE WHEN createat>='2013-11-22' and createat<'2013-11-23' THEN id ELSE NULL END)   AS day_1_count,
  COUNT(CASE WHEN createat>='2013-11-23' and createat<'2013-11-24' THEN id ELSE NULL END)   AS day_2_count,
  COUNT(CASE WHEN createat>='2013-11-24' and createat<'2013-11-25' THEN id ELSE NULL END)   AS day_3_count
FROM
  table1
GROUP BY
  level
WHERE
  createat>='2013-11-22' and createat<'2013-11-25'

不过，加入包含您需要的日期的表格可能更有意义，而不是硬编码它们。

另外，请注意 SQL 适用于固定数量的列，如果您希望一个查询 3 天然后重复使用 5 天，这将不起作用。为此，您需要将其保留为每行一个结果。

【讨论】：

【解决方案2】：

试试这个：

SELECT t.level, SUM(CASE WHEN DATE(createat) = '2013-11-22' THEN 1 ELSE 0 END) AS day1,
       SUM(CASE WHEN DATE(createat) = '2013-11-23' THEN 1 ELSE 0 END) AS day2,
       SUM(CASE WHEN DATE(createat) = '2013-11-24' THEN 1 ELSE 0 END) AS day3
FROM table1 t
WHERE DATE(t.createat) >= "2013-11-22" AND DATE(t.createat) <= "2013-11-24" 
GROUP BY t.level;

或

SELECT t.level, SUM(CASE WHEN t.createat >= "2013-11-22 00:00:00" AND t.createat <= "2013-11-22 23:59:59" THEN 1 ELSE 0 END) AS day1,
       SUM(CASE WHEN t.createat >= "2013-11-23 00:00:00" AND t.createat <= "2013-11-23 23:59:59" THEN 1 ELSE 0 END) AS day2,
       SUM(CASE WHEN t.createat >= "2013-11-24 00:00:00" AND t.createat <= "2013-11-24 23:59:59" THEN 1 ELSE 0 END) AS day3
FROM table1 t
WHERE t.createat >= "2013-11-22 00:00:00" AND t.createat <= "2013-11-24 23:59:59" 
GROUP BY t.level;

【讨论】：

【解决方案3】：

对您发布的查询的简单编辑是：

select count(ID), level 
from table1 
where createat >= "2013-11-22 00:00:00" and createat <= "2013-11-22 23:59:59" 
group by level
union
select count(ID), level 
from table1 
where createat >="2013-11-23 00:00:00" and createat <= "2013-11-23 23:59:59" 
group by level
union
select count(ID), level 
from table1 
where createat >= "2013-11-24 00:00:00" and createat <= "2013-11-24 23:59:59" 
group by level

但是，如果您尝试获取每天的计数、级别值和日期，则可以使用如下查询：

SELECT COUNT(*), level, CAST(createat AS DATE)
FROM table1
GROUP BY level, CAST(createat AS DATE)

【讨论】：