Most Occurring Value

Mike Ginsburg wrote:

There is probably a really simple solution for this problem, but
for the life of me I can't see to think of it. I have three tables

--contains u/p for all users in the site TABLE users (user_id INT
primary key, username VARCHAR(50), password TEXT) --list of all
possible events (login, logout, timeout) TABLE events (event_id INT
primary key, event VARCHAR(255)) --logs the activity of all users
logging in/out, etc TABLE log (log_id INT primary key, user_id INT
REFERENCES users, event_id INT REFERENCES event);

How would I query to find out which user has the most activity?
SELECT user_id, COUNT(event_id) FROM log GROUP BY (user_id) HAVNG
COUNT(event_id) = ???

Any and all help is appreciated. Thank you.

I'd say...

SELECT user_id, count(event_id) AS event_count FROM log GROUP BY
user_id ORDER BY event_count DESC LIMIT 1;

Or something to that effect.

Colin

Mike Ginsburg <mginsburg@collaborativefusion.com> writes:

There is probably a really simple solution for this problem, but for
the life of me I can't see to think of it. I have three tables

--contains u/p for all users in the site
TABLE users (user_id INT primary key, username VARCHAR(50), password TEXT)
--list of all possible events (login, logout, timeout)
TABLE events (event_id INT primary key, event VARCHAR(255))
--logs the activity of all users logging in/out, etc
TABLE log (log_id INT primary key, user_id INT REFERENCES users,
event_id INT REFERENCES event);

How would I query to find out which user has the most activity?
SELECT user_id, COUNT(event_id)
FROM log
GROUP BY (user_id)
HAVNG COUNT(event_id) = ???

SELECT user_id, max(count(event_id))
FROM log
GROUP BY user_id;

or

SELECT user_id, count(event_id)
FROM log
GROUP BY user_id
ORDER BY count(event_id) DESC
LIMIT 1;

Regards.

P.S. It'd be better if you can send such questions to pgsql-sql mailing
list.

Volkan YAZICI escreveu:

Mike Ginsburg <mginsburg@collaborativefusion.com> writes:

There is probably a really simple solution for this problem, but for
the life of me I can't see to think of it. I have three tables

--contains u/p for all users in the site
TABLE users (user_id INT primary key, username VARCHAR(50), password TEXT)
--list of all possible events (login, logout, timeout)
TABLE events (event_id INT primary key, event VARCHAR(255))
--logs the activity of all users logging in/out, etc
TABLE log (log_id INT primary key, user_id INT REFERENCES users,
event_id INT REFERENCES event);

How would I query to find out which user has the most activity?
SELECT user_id, COUNT(event_id)
FROM log
GROUP BY (user_id)
HAVNG COUNT(event_id) = ???

SELECT user_id, max(count(event_id))

max(count() is invalid.
aggregate function calls may not be nested

FROM log
GROUP BY user_id;

or

SELECT user_id, count(event_id)
FROM log
GROUP BY user_id
ORDER BY count(event_id) DESC
LIMIT 1;

If more than 1 user has the most activity only one is listed.

Try:

SELECT user_id, COUNT(event_id)
FROM log
GROUP BY (user_id)
HAVING COUNT(event_id) = (SELECT max(l.ct) FROM
(SELECT count(event_id) AS ct FROM log GROUP BY user_id) AS l)
ORDER BY user_id;

Osvaldo