我有一个类似于以下内容的数据集:
CREATE TABLE revenue (
employee_id int,
job_id int,
date date,
revenue numeric (9,2)
);
INSERT INTO revenue (employee_id, job_id, date, revenue) VALUES (1, 123, '2018-07-16', 100);
INSERT INTO revenue (employee_id, job_id, date, revenue) VALUES (1, 124, '2018-07-17', 100);
INSERT INTO revenue (employee_id, job_id, date, revenue) VALUES (2, 125, '2018-07-14', 100);
INSERT INTO revenue (employee_id, job_id, date, revenue) VALUES (2, 126, '2018-07-16', 100);
我编写了以下查询,并具有以下输出:
SELECT employee_id, generate_series::date, SUM(revenue) as revenue
FROM generate_series('2018-07-14'::date, '2018-07-17'::date, '1 day')
LEFT JOIN revenue ON revenue.date = generate_series::date
GROUP BY employee_id, generate_series::date
ORDER BY employee_id, generate_series::date;
+---------------+-------------------+-----------+
| employee_id | generate_series | revenue |
|---------------+-------------------+-----------|
| 1 | 2018-07-16 | 100.00 |
| 1 | 2018-07-17 | 100.00 |
| 2 | 2018-07-14 | 100.00 |
| 2 | 2018-07-16 | 100.00 |
| <null> | 2018-07-15 | <null> |
+---------------+-------------------+-----------+
SELECT 5
Time: 0.010s
super>
但是我的目标是即使没有收入也要为所有员工提供所有约会。
这是我想要的输出:
+---------------+-------------------+-----------+
| employee_id | generate_series | revenue |
|---------------+-------------------+-----------|
| 1 | 2018-07-14 | 0.00 |
| 1 | 2018-07-15 | 0.00 |
| 1 | 2018-07-16 | 100.00 |
| 1 | 2018-07-17 | 100.00 |
| 2 | 2018-07-14 | 100.00 |
| 2 | 2018-07-15 | 0.00 |
| 2 | 2018-07-16 | 100.00 |
| 2 | 2018-07-17 | 0.00 |
+---------------+-------------------+-----------+
有人知道如何实现这一目标吗?
答案 0 :(得分:2)
使用cross join
生成行,然后使用left join
引入数据:
select e.employee_id, gs.dte, coalesce(revenue, 0) as revenue
from generate_series('2018-07-14'::date, '2018-07-17'::date, '1 day') gs(dte) cross join
(select distinct employee_id from revenue) e left join
revenue r
on r.employee_id = e.employee_id and r.date = gs.dte
order by employee_id, gs.date;
我认为group by
是不必要的。每个员工和日期最多只能有一行。