[英]Mysql - Merge rows with unique value - group and count them
I have some trouble getting my query right for a specific output. 我在正确查询特定输出时遇到一些麻烦。
My table looks like this: 我的桌子看起来像这样:
ID | meta_value | field_id | item_id
------------------------------------
1 | Steve | 75 | 5
2 | Johnsson | 76 | 5
3 | Sick | 705 | 5
4 | John | 75 | 6
5 | Doe | 76 | 6
6 | Sick | 705 | 6
7 | Laura | 75 | 7
8 | Jenner | 76 | 7
9 | Sick | 705 | 7
10 | Laura | 75 | 8
11 | Jenner | 76 | 8
12 | Vacation | 705 | 8
13 | Steve | 75 | 9
14 | Johnsson | 76 | 9
15 | Sick | 705 | 9
And I want to merge - group by item_id and their combined meta_value - and count the results, where the value is "Sick" - Order by count, as follows: 我要合并-按item_id及其组合的meta_value-分组并计算结果,其中值为“病”-按计数顺序,如下所示:
Name: Sick (Count):
Steve Johnsson 2
John Doe 1
Laura Jenner 1
(Vacation is left out) (假期除外)
I think I've tried all possible combination, but obviously nothing seems to be right. 我想我已经尝试了所有可能的组合,但是显然没有什么是对的。 (Changing the table is not an option).
(更改表不是一种选择)。 I've been trying for hours...
我已经尝试了几个小时了...
Please help :) 请帮忙 :)
Thanks in advance! 提前致谢!
Try two levels of aggregation: 尝试两种聚合级别:
select first_name, last_name, count(*)
from (select max(case when field_id = 75 then meta_value end) as first_name,
max(case when field_id = 76 then meta_value end) as last_name,
max(case when field_id = 705 then meta_value end) as reason
from t
group by item_id
) t
where reason = 'sick'
group by first_name, last_name
order by count(*) desc;
Key value tables are ugly, but usually they have at least a grouping column. 键值表很丑陋,但通常它们至少有一个分组列。 Yours doesn't.
你的不是。 You must find out first which item_ids represent the same user by looking up the names.
您必须先通过查找名称来找出哪些item_ids代表同一用户。 (And hoping there aren't two different John Smith in the table.)
(希望表中没有两个不同的约翰·史密斯。)
You'd aggregate per user_id first, then aggregate again per name: 您先按照user_id进行汇总,然后再按名称再次进行汇总:
select
name,
sum(item_sick_count) as sick_count
from
(
select
concat(
any_value(case when field_id = 75 then meta_value),
' ',
any_value(case when field_id = 76 then meta_value)
) as name,
sum(field_id = 705 and meta_value = 'Sick') as item_sick_count
from mytable
group by item_id
)
group by name
order by sick_count desc, name;
The sick_count
formula makes use of MySQL's true = 1, false = 0. sick_count
公式使用MySQL的true = 1,false = 0。
Join the table with itself once for every field: 对于每个字段,将表与自身连接一次:
select
f.meta_value as first_name,
l.meta_value as last_name,
count(*) as sick_count
from eav s
join eav f using(item_id)
join eav l using(item_id)
where s.field_id = 705
and s.meta_value = 'Sick'
and f.field_id = 75
and l.field_id = 76
group by first_name, last_name
order by sick_count desc
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