如何按时间段（例如小时）选择每个用户的计数？

Question

如何编写Postgresql查询以按小时查找用户的计数？

表：

date     name 
------------------- ---- 
2015-01-01 23:11:11 John 
2015-02-02 23:22:22 John 
2015-02-02 23:00:00 Mary 
2015-02-02 23:59:59 Mary 
2015-03-03 00:33:33 Mary 

所需的输出：

 hour   | name | count 
---------------------+---------+------- 
2015-01-01 23:00:00 | John |  1 
2015-02-02 23:00:00 | Mary |  2 
2015-02-02 23:00:00 | John |  1 
2015-03-03 00:00:00 | Mary |  1 

我想这http://www.sqlfiddle.com/#!12/a50d4/2：

CREATE TABLE my_table (
    date TIMESTAMP WITHOUT TIME ZONE, 
    name TEXT 
); 
INSERT INTO my_table (date, name) VALUES ('2015-01-01 23:11:11', 'John'); 
INSERT INTO my_table (date, name) VALUES ('2015-02-02 23:22:22', 'John'); 
INSERT INTO my_table (date, name) VALUES ('2015-02-02 23:00:00', 'Mary'); 
INSERT INTO my_table (date, name) VALUES ('2015-02-02 23:59:59', 'Mary'); 
INSERT INTO my_table (date, name) VALUES ('2015-03-03 00:33:33', 'Mary'); 

SELECT DISTINCT 
     date_trunc('hour', "date") AS hour, 
     name, 
     count(*) OVER (PARTITION BY date_trunc('hour', "date")) AS count 
FROM my_table 
ORDER BY hour, count; 

，但它给了我：

hour    | name | count | 
---------------------|------|-------| 
2015-01-01 23:00:00 | John |  1 | 
2015-02-02 23:00:00 | Mary |  3 | 
2015-02-02 23:00:00 | John |  3 | 
2015-03-03 00:00:00 | Mary |  1 | 

类似：

• Select distinct users group by time range
• PostgreSQL: running count of rows for a query 'by minute'

Answer 1

如果你想坚持的窗口功能，你需要添加 “名” 到你的列表像这样：

http://www.sqlfiddle.com/#!12/a50d4/51

SELECT DISTINCT 
    date_trunc('hour', "date") AS "hour", 
    name, 
    count(name) OVER (PARTITION BY name, date_trunc('hour', "date")) AS "cnt" 
FROM my_table 
ORDER BY hour, cnt DESC 

Answer 2

select 
    date_trunc('hour', "date") as "hour", 
    name, 
    count(*) as "count" 
from my_table 
group by 1, 2 
order by 1, 3 desc; 

http://www.sqlfiddle.com/#!12/a50d4/62

Answer 3

我认为你正在寻找这个

SELECT DISTINCT 
     date_trunc('hour', "date") AS hour, 
     name, 
     count(*) as tcount 
FROM my_table 
GROUP BY hour,name 
ORDER BY hour, count(*) Desc 

输出：

 hour   | name | count 
---------------------+---------+------- 
2015-01-01 23:00:00 | John |  1 
2015-02-02 23:00:00 | Mary |  2 
2015-02-02 23:00:00 | John |  1 
2015-03-03 00:00:00 | Mary |  1 

SQLFIDDLE

Answer 4

这为我工作：http://www.sqlfiddle.com/#!12/a50d4/57

SELECT DISTINCT name, 
       date_trunc('hour', date) as hour, 
       count(*) as count 
FROM my_table 
GROUP BY name, hour 
ORDER BY hour, count DESC;