join table with itself to create more row - oracle

Question

me has a table which has following data in TABLE1
me wanted to make sure all teh name has all "work type" available for all those dates only which is in teh data. Output should like TABLE2
me tried to put a query like
select t1.name,t1.date,mt.work_type,t1.minutes
from table1 t1
right join (select distinct work_type from t1) mt on t1.work_type=mt.work_type
however it didn't work. Please halp

Answer 1

You need to join with a subquery that cross joins all the names, dates and work types.
SELECT mt.name, mt.date, mt.work_type, COALESCE(t1.minutes, 0) AS minutes
FROM (
SELECT DISTINCT t1.name, t1.date, t2.work_type
FROM table1 AS t1
CROSS JOIN table1 AS t2
) AS mt
LEFT JOIN table1 AS t1
ON t1.name = mt.name AND t1.date = mt.date AND t1.work_type = mt.work_type
ORDER BY mt.name, mt.date, mt.work_type
Note that in the subquery you have to specify the actual table name, not the alias from the main query.
DEMO

Answer 2

In Oracle, you can use a partitioned outer join:
SELECT t.name,
t."DATE",
w.work_type,
COALESCE(t.minutes, 0) AS minutes
FROM (SELECT DISTINCT work_type FROM table1) w
LEFT OUTER JOIN table1 t
PARTITION BY (t.name, t."DATE")
ON (w.work_type = t.work_type)
Which, for the sample data:
CREATE TABLE table1 (name, "DATE", work_type, minutes) AS
SELECT 'a', DATE '2011-01-01', 'labor', 53 FROM DUAL UNION ALL
SELECT 'a', DATE '2011-01-01', 'private', 58 FROM DUAL UNION ALL
SELECT 'a', DATE '2011-01-01', 'other', 19 FROM DUAL UNION ALL
SELECT 'b', DATE '2011-01-02', 'labor', 31 FROM DUAL UNION ALL
SELECT 'b', DATE '2011-01-02', 'other', 24 FROM DUAL UNION ALL
SELECT 'b', DATE '2011-01-01', 'private', 19 FROM DUAL UNION ALL
SELECT 'c', DATE '2011-01-03', 'labor', 25 FROM DUAL UNION ALL
SELECT 'c', DATE '2011-01-03', 'private', 50 FROM DUAL UNION ALL
SELECT 'c', DATE '2011-01-01', 'private', 23 FROM DUAL UNION ALL
SELECT 'd', DATE '2011-01-01', 'other', 20 FROM DUAL;
Outputs:
NAME
DATE
WORK_TYPE
MINUTES
a
01-JAN-11
labor
53
a
01-JAN-11
other
19
a
01-JAN-11
private
58
b
01-JAN-11
labor
0
b
01-JAN-11
other
0
b
01-JAN-11
private
19
b
02-JAN-11
labor
31
b
02-JAN-11
other
24
b
02-JAN-11
private
0
c
01-JAN-11
labor
0
c
01-JAN-11
other
0
c
01-JAN-11
private
23
c
03-JAN-11
labor
25
c
03-JAN-11
other
0
c
03-JAN-11
private
50
d
01-JAN-11
labor
0
d
01-JAN-11
other
20
d
01-JAN-11
private
0
db<>fiddle here
In MySQL, you can use:
SELECT nd.name,
nd.date,
w.work_type,
COALESCE(t.minutes, 0) AS minutes
FROM (SELECT DISTINCT work_type FROM table1) w
CROSS JOIN
(SELECT DISTINCT name, date FROM table1) nd
LEFT OUTER JOIN table1 t
ON (t.name = nd.name AND t.date = nd.date AND t.work_type = w.work_type);
db<>fiddle here