Select and count data per day [duplicate] - mysql

Question

This question already has answers here:
generate days from date range
(30 answers)
Closed 3 years ago.
I have a following table with columns:
id | number | created_at
1 | A11 | 2020-01-01 06:08:19
2 | A21 | 2020-01-04 06:08:19
How do I query all the data in a date range from specific date and count all data per day?
I tried something like that :
SELECT DATE_FORMAT(created_at, '%Y-%m-%d') AS the_date , COUNT(*) AS count
FROM `transactions`
WHERE created_at BETWEEN DATE_FORMAT('2020-01-01', '%Y-%m-%d') AND DATE_FORMAT('2020-01-04', '%Y-%m-%d')
GROUP BY the_date
Then i got data like that :
the_date | count
2020-01-01 | 1
2020-01-04 | 1
I want to achieve
the_date | count
2020-01-01 | 1
2020-01-02 | 0
2020-01-03 | 0
2020-01-04 | 1

Answer 1

if your version is below mysql 8.0 then you can use this script :
step1 : create a sequence N rows table :
create table sequence(id int);
create procedure insert_data_proc(in v_i int)
begin
declare i int default 0;
while i < v_i
do
insert into sequence values (i);
set i = i + 1;
end while;
end;
call insert_data_proc(1000);
drop procedure insert_data_proc;
step2 : query the table and left join your table's by mindate,maxdate,datediff
select
t1.created_at the_date
,case when count is null then 0 else count end as count
from (
select date_add(t2.mincreated_at , interval id day) created_at
from sequence t1
left join (
select datediff(max(created_at),min(created_at)) diff
,date(min(created_at) ) mincreated_at
,date(max(created_at) ) maxcreated_at
from transactions
) t2 on 1=1
where t1.id < t2.diff+1
) t1
left join (
select date(created_at) created_at,count(1) count
from transactions
group by date(created_at)
) t2 on t1.created_at = t2.created_at
order by the_date
note : if your data's days over 1000 day then you only need to increase the SP value.
[Online Demo Link MySQL 5.7 | db<>fiddle](https://dbfiddle.uk/?rdbms=mysql_5.7&fiddle=57d3e60bb2b918e8b6d2d8f3d5e63a6c
)

Answer 2

you can use like this :
SET #date_min = '2019-01-01';
SET #date_max = '2019-01-04';
SELECT
date_generator.date as the_date,
IFNULL(COUNT(transactions.id), 0) as count
from (
select DATE_ADD(#date_min, INTERVAL (#i:=#i+1)-1 DAY) as `date`
from information_schema.columns,(SELECT #i:=0) gen_sub
where DATE_ADD(#date_min,INTERVAL #i DAY) BETWEEN #date_min AND #date_max
) date_generator
left join transactions on DATE(created_at) = date_generator.date
GROUP BY date;
so here I am creating a temporary table date_generator will dates in between of given date range and join to with your main table (transactions).
output as expected:
the_date | count
2020-01-01 | 1
2020-01-02 | 0
2020-01-03 | 0
2020-01-04 | 1

Answer 3

I will give a suggestion for you to do this,
1 Solution
Create temporary table and add the dates and then join with the transactions table
create temporary table tempcalander
as
select * from
(select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) dates from
(select 0 i 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 i 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 i 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 i 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 i 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 dates between '2020-01-01' and '2020-01-04';
SELECT DATE_FORMAT(dates, '%Y-%m-%d') AS the_date , COUNT(created_at) AS count
FROM transactions t right join tempcalander c on t.created_at = c.dates
WHERE dates BETWEEN DATE_FORMAT('2020-01-01', '%Y-%m-%d') AND DATE_FORMAT('2020-01-04', '%Y-%m-%d')
GROUP BY the_date
2 Solution
you can create a separate table to add your dates.
CREATE TABLE calendar
(
dates date PRIMARY KEY
) ;
Then add you dates to this table,
INSERT INTO
calendar (dates)
VALUES
('2020-01-01'),
('2020-01-02'),
('2020-01-03'),
('2020-01-04'),
('2020-01-05'),
('2020-01-06') ;
after you can join the the transactions table with the calendar table and get the output
SELECT DATE_FORMAT(dates, '%Y-%m-%d') AS the_date , COUNT(created_at) AS count
FROM transactions t right join calendar c on t.created_at = c.dates
WHERE dates BETWEEN DATE_FORMAT('2020-01-01', '%Y-%m-%d') AND DATE_FORMAT('2020-01-04', '%Y-%m-%d')
GROUP BY the_date