SQL 按几个字段分组答案

【问题标题】：SQL group by several fieldsSQL 按几个字段分组
【发布时间】：2020-07-27 01:13:06
【问题描述】：

为什么会出现这个错误？

"代码: 43, e.displayText() = DB::Exception: 非法类型 (Enum8('' = 0, 'Manhattan' = 1, 'Bronx' = 2, 'Brooklyn' = 3, 'Queens' = 4, 'Staten Island' = 5)) 的 2 个函数参数和 (version 20.3.4.10 (official build))"

select pickup_boroname as region, toHour(pickup_datetime) as time_, count(payment_type_) as pay_count
from datasets.trips_mergetree
where pickup_date between '2011-01-01' and '2011-12-31' and
      pickup_boroname != 0
group by time_ and region
order by pay_count desc;

【问题讨论】：

表中有出租车数据：pickup_boroname - 城市区域(enum8) Pickup_date - 行程数据；pickup_datetime - 行程数据和时间；我无法按时间和地区计算付款：
表格有列，而不是字段。
如果你在 where 子句中写：pickup_boroname != '' 而不是picking_boroname != 0 是否有效？还有这些列的列类型是什么？
@Sourcery，它是 enum8 : "" - 0（空字符串），'Manhattan' - 1 等等
如果有人有同样的问题，错误是因为group by time_ and region，我必须写group by time_ , region

标签： mysql sql database clickhouse

【解决方案1】：

Group by 通常不会采用布尔表达式。我想你想要：

select pickup_boroname as region, toHour(pickup_datetime) as time_, 
       count(payment_type_) as pay_count
from datasets.trips_mergetree
where pickup_date between '2011-01-01' and '2011-12-31' and
      pickup_boroname <> 0
group by time_, region
order by pay_count desc;

我将!= 替换为<>，但也可能存在问题，具体取决于pickup_boroname 的类型。您可能打算：

pickup_boroname is not null

【讨论】：

pickup_boroname 的类型为 Enum8('' = 0, 'Manhattan' = 1, 'Bronx' = 2, 'Brooklyn' = 3, 'Queens' = 4, 'Staten Island' = 5) ) 的 2 个函数参数和 (version 20.3.4.10 (official build))"，即picking_boroname != 0 是必要的，以忽略区域不是空字符串的行程（枚举中的空字符串对应于 0）。我试过你的决定，但它没有帮助
@iamhdq 。 . .你用pickup_boroname is not null了吗？
是的，我认为问题不在这里，因为如果我只写 where pickup_date between '2011-01-01' and '2011-12-31' 而没有 "pickup_boroname != 0" ，错误是一样的

【解决方案2】：

这是一个错误。尝试最新的稳定版本 20.3.5.21

SELECT
    pickup_boroname AS region,
    toHour(pickup_datetime) AS time_,
    count(payment_type_) AS pay_count
FROM trips_mergetree
WHERE ((pickup_date >= '2011-01-01') AND (pickup_date <= '2011-12-31')) AND (pickup_boroname != 0)
GROUP BY
    time_,
    region
ORDER BY pay_count DESC

Ok.

0 rows in set. Elapsed: 0.002 sec.

【讨论】：

非常感谢！我在 Ubuntu 中更新了 datagrip，似乎没有修复错误，但在 Windows 中它可以工作。再次感谢！