PostgreSQL:按时间间隔计数记录 [英] Postgresql: count records by time intervals
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问题描述
我正在尝试将以下SQL语句与postgresql一起使用以生成一些报告:
I am trying to use the following SQL statement with postgresql to generate some report:
WITH GRID AS (
SELECT START_TIME, LEAD(START_TIME) OVER (ORDER BY START_TIME) AS END_TIME
FROM (
SELECT GENERATE_SERIES('2015-08-01 12:00:00', '2015-09-01 12:00:00', INTERVAL '1 day') AS START_TIME
FROM MY_TABLE
) x
)
SELECT
START_TIME, COUNT(MY_TABLE._ID) AS COUNT
FROM
GRID
LEFT JOIN MY_TABLE ON MY_TABLE.CREATED >= GRID.START_TIME AND MY_TABLE.CREATED < GRID.END_TIME
WHERE MY_TABLE.COMPANY_ID = '1001' AND MY_TABLE.CUSTOMER_ID = '1003'
GROUP BY 1 ORDER BY 1
我期望的是:
- "2015-08-01 12:00:00 + 02"; 0
- "2015-08-02 12:00:00 + 02"; 1
- "2015-08-03 12:00:00 + 02"; 0
- "2015-08-04 12:00:00 + 02"; 1
- "2015-08-05 12:00:00 + 02"; 0
- ....
- "2015-08-31 12:00:00 + 02"; 0
但实际结果是:
- "2015-08-02 12:00:00 + 02"; 1
- "2015-08-04 12:00:00 + 02"; 1
它只是跳过计数为0的记录.
it simply skips the records with 0 count.
如果我不指定where子句(条件部分),则可以获得预期的结果.
if I don't specify the where clause (condition part), I could get the expected result.
有人可以帮我吗?
谢谢!
推荐答案
以下查询似乎可以满足您的要求:
Folllowing query seems do what you want:
WITH GRID AS
(
SELECT
START_TIME,
LEAD(START_TIME) OVER (ORDER BY START_TIME) AS END_TIME
FROM
(
SELECT
GENERATE_SERIES('2015-08-01 12:00:00', '2015-09-01 12:00:00', INTERVAL '1 day') AS START_TIME
FROM MY_TABLE
) x
)
SELECT
START_TIME,
COUNT(MY_TABLE._ID) AS COUNT
FROM GRID
LEFT JOIN MY_TABLE ON
MY_TABLE.CREATED >= GRID.START_TIME AND
MY_TABLE.CREATED < GRID.END_TIME AND
MY_TABLE.COMPANY_ID = '1001' AND
MY_TABLE.CUSTOMER_ID = '1003'
GROUP BY 1
ORDER BY 1
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