Postgres 13

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CREATE TABLE t (
    starttime timestamp
);

INSERT INTO t VALUES
('2020-11-25 00:10:00'),
('2020-11-25 00:58:00'),
('2020-11-25 10:10:00'),
('2020-11-25 23:15:00'),
('2020-11-25 23:10:00'),
('2020-11-25 23:50:00'),
('2020-11-25 23:55:00');

CREATE TABLE



INSERT 0 7


SELECT
    date_trunc('hour', starttime),
    COUNT(*)
FROM 
    t
GROUP BY 1


date_trunc
count


2020-11-25 00:00:00
2

2020-11-25 10:00:00
1

2020-11-25 23:00:00
4



SELECT 3


SELECT
    to_char(date_trunc('hour', starttime), 'HH12:MI:SS AM') || ' - ' || to_char(date_trunc('hour', starttime)  + interval '1 hour', 'HH12:MI:SS AM'),
    COUNT(*)
FROM 
    t
GROUP BY date_trunc('hour', starttime)


?column?
count


12:00:00 AM - 01:00:00 AM
2

10:00:00 AM - 11:00:00 AM
1

11:00:00 PM - 12:00:00 AM
4



SELECT 3

date_trunc	count
2020-11-25 00:00:00	2
2020-11-25 10:00:00	1
2020-11-25 23:00:00	4

?column?	count
12:00:00 AM - 01:00:00 AM	2
10:00:00 AM - 11:00:00 AM	1
11:00:00 PM - 12:00:00 AM	4