MariaDB 10.3

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create table some_table(
    date_field date,
    person char(10)
)
;
insert into some_table values ('2021-11-01','Ivanov');
insert into some_table values ('2021-11-11','Ivanov');
insert into some_table values ('2021-11-01','Petrov');
insert into some_table values ('2021-11-11','Sidorov');
insert into some_table values ('2021-11-15','Ivanov');
insert into some_table values ('2021-11-05','Sidorov');
select * from some_table;


date_field
person


2021-11-01
Ivanov

2021-11-11
Ivanov

2021-11-01
Petrov

2021-11-11
Sidorov

2021-11-15
Ivanov

2021-11-05
Sidorov


select cal.cal_date, count(person)
  from some_table st
  right join (
  -- генерируем календарь - набор дат
    select *
      from (
        select adddate('1970-01-01',t4*10000 + t3*1000 + t2*100 + t1*10 + t0) cal_date
          from
            (select 0 t0 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
            (select 0 t1 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
            (select 0 t2 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
            (select 0 t3 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
            (select 0 t4 union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4
      ) v
      where cal_date between '2021-11-01' and '2021-11-30'
  ) cal on cal.cal_date = st.date_field
  group by cal.cal_date
;


cal_date
count(person)


2021-11-01
2

2021-11-02
0

2021-11-03
0

2021-11-04
0

2021-11-05
1

2021-11-06
0

2021-11-07
0

2021-11-08
0

2021-11-09
0

2021-11-10
0

2021-11-11
2

2021-11-12
0

2021-11-13
0

2021-11-14
0

2021-11-15
1

2021-11-16
0

2021-11-17
0

2021-11-18
0

2021-11-19
0

2021-11-20
0

2021-11-21
0

2021-11-22
0

2021-11-23
0

2021-11-24
0

2021-11-25
0

2021-11-26
0

2021-11-27
0

2021-11-28
0

2021-11-29
0

2021-11-30
0


SELECT '2021-11-01' + INTERVAL seq DAY FROM seq_0_to_29;


'2021-11-01' + INTERVAL seq DAY


2021-11-01

2021-11-02

2021-11-03

2021-11-04

2021-11-05

2021-11-06

2021-11-07

2021-11-08

2021-11-09

2021-11-10

2021-11-11

2021-11-12

2021-11-13

2021-11-14

2021-11-15

2021-11-16

2021-11-17

2021-11-18

2021-11-19

2021-11-20

2021-11-21

2021-11-22

2021-11-23

2021-11-24

2021-11-25

2021-11-26

2021-11-27

2021-11-28

2021-11-29

2021-11-30


select cal.cal_date, count(person)
  from some_table st
  right join (
  -- генерируем календарь - набор дат
    SELECT '2021-11-01' + INTERVAL seq DAY as cal_date FROM seq_0_to_29
  ) cal on cal.cal_date = st.date_field
  group by cal.cal_date
;


cal_date
count(person)


2021-11-01
2

2021-11-02
0

2021-11-03
0

2021-11-04
0

2021-11-05
1

2021-11-06
0

2021-11-07
0

2021-11-08
0

2021-11-09
0

2021-11-10
0

2021-11-11
2

2021-11-12
0

2021-11-13
0

2021-11-14
0

2021-11-15
1

2021-11-16
0

2021-11-17
0

2021-11-18
0

2021-11-19
0

2021-11-20
0

2021-11-21
0

2021-11-22
0

2021-11-23
0

2021-11-24
0

2021-11-25
0

2021-11-26
0

2021-11-27
0

2021-11-28
0

2021-11-29
0

2021-11-30
0

date_field	person
2021-11-01	Ivanov
2021-11-11	Ivanov
2021-11-01	Petrov
2021-11-11	Sidorov
2021-11-15	Ivanov
2021-11-05	Sidorov

cal_date	count(person)
2021-11-01	2
2021-11-02	0
2021-11-03	0
2021-11-04	0
2021-11-05	1
2021-11-06	0
2021-11-07	0
2021-11-08	0
2021-11-09	0
2021-11-10	0
2021-11-11	2
2021-11-12	0
2021-11-13	0
2021-11-14	0
2021-11-15	1
2021-11-16	0
2021-11-17	0
2021-11-18	0
2021-11-19	0
2021-11-20	0
2021-11-21	0
2021-11-22	0
2021-11-23	0
2021-11-24	0
2021-11-25	0
2021-11-26	0
2021-11-27	0
2021-11-28	0
2021-11-29	0
2021-11-30	0