Database: version 8.0.26-17 https://www.percona.com/doc/percona-server/8.0/release-notes/Percona-Server-8.0.26-17.html
I have two queries that yield different results. I don't understand why.
1)
select eev_company_id,
count(distinct maj.dsd_prefix) as maj_cnt,
count(distinct min.dsd_prefix) as min_cnt
from ehev_most_recent as eev
inner join ekohubschema as ehs on ehs.ehs_subcategory = eev.eev_subcategory
left join datasourcedescription as maj on maj.dsd_prefix = eev.eev_prefix and maj.dsd_type_id = 'MAJ'
left join datasourcedescription as min on min.dsd_prefix = eev.eev_prefix and min.dsd_type_id <> 'MAJ'
where ehs.ehs_category <> 'Exclusionary Factors'
group by eev.eev_company_id
having eev.eev_company_id = 'ADD53604';
result is:
+----------------+---------+---------+
| eev_company_id | maj_cnt | min_cnt |
+----------------+---------+---------+
| ADD53604 | 2 | 1 |
+----------------+---------+---------+
The second query is pretty much the same but substituted group by eev_company_id having with AND:
2)
select
count(distinct maj.dsd_prefix) as maj_cnt,
count(distinct min.dsd_prefix) as min_cnt
from ehev_most_recent as eev
inner join ekohubschema as ehs on ehs.ehs_subcategory = eev.eev_subcategory
left join datasourcedescription as maj on maj.dsd_prefix = eev.eev_prefix and maj.dsd_type_id = 'MAJ'
left join datasourcedescription as min on min.dsd_prefix = eev.eev_prefix and min.dsd_type_id <> 'MAJ'
where ehs.ehs_category <> 'Exclusionary Factors' AND eev.eev_company_id = 'ADD53604';
This query results in:
+---------+---------+
| maj_cnt | min_cnt |
+---------+---------+
| 2 | 0 |
+---------+---------+
As you can see, the min_cnt here is 0 while for the first query it is 1. What is the reason for the difference?
If I remove ekohubschema join I get the same results:
3)
select eev_company_id,
count(distinct maj.dsd_prefix) as maj_cnt,
count(distinct min.dsd_prefix) as min_cnt
from ehev_most_recent as eev
left join datasourcedescription as maj on maj.dsd_prefix = eev.eev_prefix and maj.dsd_type_id = 'MAJ'
left join datasourcedescription as min on min.dsd_prefix = eev.eev_prefix and min.dsd_type_id <> 'MAJ'
group by eev.eev_company_id
having eev.eev_company_id = 'ADD53604';
+----------------+---------+---------+
| eev_company_id | maj_cnt | min_cnt |
+----------------+---------+---------+
| ADD53604 | 2 | 0 |
+----------------+---------+---------+
ekohubschema table has the following columns: ehs_category, ehs_subcategory and ehs_long_description, no company ID whatsoever, and yet it interferes with the result.
I don't see any minor datasources, only major. This is why I struggle to find out where the count 1 (for min_cnt ) comes from.
