mysql - Get all Date of month along with data from table

Question

I have two tables user_profile and tracked_search. The user_profile table has user details and tracked_search tracks searches made by each user.

Whenever a user makes a search this search entry goes in the tracked_search table. If nothing is searched for a particular date nothing is added in tracked_search.

I need to develop a report where in I need to show on all days of month how many users made searches.

For example:

CREATE TABLE tracked_search (
    id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
    created DATE,
    user_id int NOT NULL
);

INSERT INTO tracked_search(created, user_id) VALUES
('2017-10-01', 1000),
('2017-10-01', 1000),
('2017-10-01', 2000),
('2017-10-01', 3000),
('2017-10-01', 4000),
('2017-10-04', 1000),
('2017-10-04', 2000),
('2017-10-04', 2000),
('2017-10-04', 2000),
('2017-10-04', 2000),
('2017-10-04', 3000),
('2017-10-31', 1000),
('2017-10-31', 2000),
('2017-10-31', 3000),
('2017-10-31', 4000),
('2017-10-31', 5000);

Desired output:

Date       user_count 
2017-10-01    4
2017-10-02    0
2017-10-03    0
2017-10-04    3
2017-10-05    0
...
2017-10-30    0
2017-10-31    5

I have written following query

SELECT ts.created , count( distinct ts.user_id) FROM tracked_search ts, user_profile u
 WHERE ts.created>=(CURDATE()-INTERVAL 1 MONTH) AND u.id = ts.user_id
 group by ts.created;

but i get

Date       user_count 
2017-10-01    4
2017-10-04    3
2017-10-31    5

I need to print all days values if no entry is there for a particular date it should be zero.

I am using MySQL.

Answer 1

By the way, you don't need the join on user_profile.

If you have a dates table with the relevant dates, this is pretty easy:

SELECT dates.day AS `Date`, COUNT(DISTINCT ts.user_id) AS user_count
FROM dates
LEFT OUTER JOIN tracked_search AS ts
    ON ts.created = dates.day
GROUP BY dates.day;

Since you probably don't have a dates table and might not want to create and maintain one, you could use one of the solutions for generating the list of dates on the fly. e.g. Get a list of dates between two dates or How to get list of dates between two dates in mysql select query

SELECT dates.day AS `Date`, COUNT(DISTINCT ts.user_id) AS user_count
FROM (
    SELECT ADDDATE('1970-01-01', t4.i * 10000 + t3.i * 1000 + t2.i * 100 + t1.i * 10 + t0.i) AS day
    FROM (SELECT 0 AS i UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS t0,
         (SELECT 0 AS i UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS t1,
         (SELECT 0 AS i UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS t2,
         (SELECT 0 AS i UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS t3,
         (SELECT 0 AS i UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS t4
) AS dates
LEFT OUTER JOIN tracked_search AS ts
    ON ts.created = dates.day
WHERE dates.day >= '2017-10-01'
AND dates.day < '2017-11-01'
GROUP BY dates.day;