SQL: list rows that do not have any transactions - mysql

Question

I have a table for definition - def
Id Device Location
1 GGHY199 USA
12 DFGHY71 India
145 APPHY75 USA
And its transactions are recorded in a diff table -event
eventid deviceid event date
123 12 Login 12-01-2019
32 12 Unreachable 18-02-2019
223 145 Unreachable 19-02-2019
334 1 DOWN 01-03-2019
I want an output as
for every day, all three devices should show, if it has no transacion, it should show as null, with what i assume is the first date of the month in the date column.
like,
eventid deviceid event date
null 1 null 01-01-2019
123 12 Login 12-01-2019
null 145 null 01-01-2019
null 1 null 01-02-2019
32 12 Unreachable 18-02-2019
223 145 Unreachable 19-02-2019
334 1 DOWN 01-03-2019
null 12 null 01-03-2019
null 145 null 01-03-2019
currently im doing:
select * from def
left join
event on def.id=event.deviceid
and im obviously not getting what i want.
Thanks!

Answer 1

Assuming you have a valid calendar table for all the date you need (mimic by the select union all table t) you could try using left join between calendare and the others table
select t.date, e.eventid, e.device, e.event, d.device
from (
select '2019-01-01' date
union all
select '2019-01-02'
union all
select '2019-01-03'
.....
union all
select '2019-03-31'
) t
left event e on t.date = e.event
left join device d on e.device = d.id

Answer 2

You seem to be after something like this...
DROP TABLE IF EXISTS my_table;
CREATE TABLE my_table
(event_id SERIAL PRIMARY KEY
,device_id INT NOT NULL
,event VARCHAR(12) NOT NULL
,date DATE NOT NULL
);
INSERT INTO my_table VALUES
(123, 12,'Login','2019-01-12'),
( 32, 12,'Unreachable','2019-02-18'),
(223,145,'Unreachable','2019-02-19'),
(334, 1,'DOWN','2019-03-01');
SELECT DISTINCT z.event_id
, x.device_id
, z.event
, y.date
FROM my_table x
JOIN my_table y
LEFT
JOIN my_table z
ON z.device_id = x.device_id
AND z.date = y.date
ORDER
BY date
, device_id;
+----------+-----------+-------------+------------+
| event_id | device_id | event | date |
+----------+-----------+-------------+------------+
| NULL | 1 | NULL | 2019-01-12 |
| 123 | 12 | Login | 2019-01-12 |
| NULL | 145 | NULL | 2019-01-12 |
| NULL | 1 | NULL | 2019-02-18 |
| 32 | 12 | Unreachable | 2019-02-18 |
| NULL | 145 | NULL | 2019-02-18 |
| NULL | 1 | NULL | 2019-02-19 |
| NULL | 12 | NULL | 2019-02-19 |
| 223 | 145 | Unreachable | 2019-02-19 |
| 334 | 1 | DOWN | 2019-03-01 |
| NULL | 12 | NULL | 2019-03-01 |
| NULL | 145 | NULL | 2019-03-01 |
+----------+-----------+-------------+------------+

Answer 3

Using CTE table, we can create dates and then join them with event table.
with t0 (i) as (select 0 union all select 0 union all select 0),
t1 (i) as (select a.i from t0 a ,t0 b ),
t2 (i) as (select a.i from t1 a ,t1 b ),
t3 (srno) as (select row_number()over(order by a.i) from t2 a ,t2 b ),
tbldt(dt) as (select dateadd(day,t3.srno-1,'01/01/2019') from t3)
select eventid, deviceid, event, tbldt.dt
from tbldt
left join event e on e.date = tbldt.dt
left join def d on e.deviceid = d.id
where tbldt.dt <= (select max(date) from event)