Postgres 16

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CREATE TABLE t (
   visitor       VARCHAR(7) NOT NULL
  ,session_num   INTEGER  NOT NULL
  ,site          VARCHAR(7) NOT NULL
  ,page_view_num INTEGER  NOT NULL
  ,timestamp     VARCHAR(19) NOT NULL
);
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site A',1,'2024-03-22 11:41:10');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site A',2,'2024-03-22 11:41:14');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site A',3,'2024-03-22 11:41:16');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site B',4,'2024-03-22 11:41:47');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site B',5,'2024-03-22 11:42:18');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site B',6,'2024-03-22 11:42:19');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site C',7,'2024-03-22 11:42:55');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site C',8,'2024-03-22 11:43:18');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site C',9,'2024-03-22 11:43:31');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site A',10,'2024-03-22 11:52:19');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User A',2,'Site A',11,'2024-03-22 10:52:21');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User B',4,'Site B',1,'2024-03-25 10:52:30');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User B',4,'Site B',2,'2024-03-25 10:52:40');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User B',4,'Site A',3,'2024-03-25 10:53:50');
INSERT INTO t(visitor,session_num,site,page_view_num,timestamp) VALUES ('User B',4,'Site B',4,'2024-03-25 10:54:19');

CREATE TABLE

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

INSERT 0 1

visitor	session_num	site	page_view_num	timestamp	i	site_num
User A	2	Site A	1	2024-03-22 11:41:10	1	1
User A	2	Site A	2	2024-03-22 11:41:14	0	1
User A	2	Site A	3	2024-03-22 11:41:16	0	1
User A	2	Site B	4	2024-03-22 11:41:47	1	2
User A	2	Site B	5	2024-03-22 11:42:18	0	2
User A	2	Site B	6	2024-03-22 11:42:19	0	2
User A	2	Site C	7	2024-03-22 11:42:55	1	3
User A	2	Site C	8	2024-03-22 11:43:18	0	3
User A	2	Site C	9	2024-03-22 11:43:31	0	3
User A	2	Site A	10	2024-03-22 11:52:19	1	4
User A	2	Site A	11	2024-03-22 10:52:21	0	4
User B	4	Site B	1	2024-03-25 10:52:30	1	1
User B	4	Site B	2	2024-03-25 10:52:40	0	1
User B	4	Site A	3	2024-03-25 10:53:50	1	2
User B	4	Site B	4	2024-03-25 10:54:19	1	3

SELECT 15