MySQL query only is selecting one entry - mysql

Question

I have two tables, h_user and appointment, and this query where I want to get all the users that missed more than 3 appointments in the last trimester. I am doing it like this:
select h_user.name from h_user
inner join appointment on appointment.id_user=h_user.id
having count(appointment.missed='y' and date(appointment.datetime)>(curdate()-interval 3 month))>3;
My problem is that when I run this I am only getting one user when I should get two since I included these(the third value is not relevant here, it's the doctor's id):
insert into appointment values('2019-10-11 16:00:00','1','10','y');
insert into appointment values('2019-11-15 10:00:00','1','11','y');
insert into appointment values('2019-12-14 10:00:00','1','11','y');
insert into appointment values('2019-11-21 10:00:00','1','11','y');
insert into appointment values('2019-10-21 10:00:00','1','11','y');
insert into appointment values('2019-10-11 16:00:00','2','12','y');
insert into appointment values('2019-11-15 10:00:00','2','13','y');
insert into appointment values('2019-12-14 10:00:00','2','13','y');
insert into appointment values('2019-11-21 10:00:00','2','13','y');
insert into appointment values('2019-10-21 10:00:00','2','13','y');
Also when I delete the user the result gives me and run it again, it gives me the other one so I know it works only for one user. If anyone could help me figure out the problem that would be great, ty in advance!

Answer 1

Basially your query is missing a group by clause (which old versions of MySQL allow), so it is giving you wrong results. Just add the missing clause (you do want to include the primary key column of the users table in the group by, in case two different users have the same name).
You should move all the conditions to the where clause for efficiency. I would also recommend against using date() against a table column, since this defeats an existing index; you can get the same results without this function.
Consider:
select u.name
from h_user u
inner join appointment a on a.id_user = u.id
where a.datetime > curdate() - interval 3 month and a.missed = 'y'
group by u.id, u.name
having count(*) > 3;
Demo on DB Fiddle:
| name |
| :--- |
| foo |
| bar |

Answer 2

You are missing a group by h_user.name clause and you should also move your 2nd condition in a WHERE clause:
select h_user.name
from h_user inner join appointment on
appointment.id_user=h_user.id
where date(appointment.datetime)>(curdate()-interval 3 month)
group by h_user.name
having sum(appointment.missed='y')>3
Note that it's safer to use the user's id in a group by clause to avoid cases where 2 or more users have the same name.
So this would be better:
select h_user.id, h_user.name
.................................
group by h_user.id, h_user.name
.................................