SQL Query HELP | Advice needed !

Question

Hello everyone!
I am having trouble writing a query for the following Problem :

App usage data are kept in the following table:

TABLE sessions
id INTEGER PRIMARY KEY,
userId INTEGER NOT NULL,
duration DECIMAL NOT NULL

Write a query that selects userId and average session duration for each user who has more than one session.

I am not sure I understand how to write the query that selects a userID that appears more than one times in the table.

Any help would be great!

Answer 1

Well, for sure I found a solution that works:

SELECT userId, AVG(duration)from sessions
GROUP BY userId
HAVING COUNT(userId)>1 ;

I am quoting from w3schools :

The HAVING clause was added to SQL because the WHERE keyword
could not be used with aggregate functions.

Thank you so much Michelle and Ankit for reaching out !

Answer 2

SELECT DISTINCT userId, AVG(duration) from sessions WHERE COUNT(userId)>1;

Answer 3

i'm not sure but try this if it works:

SELECT DISTINCT userID, AVG(duration)
FROM sessions
WHERE (SELECT COUNT(userId) AS countUsers
FROM sessions
WHERE countUsers >1)

let me know if it works... i can't test it now

Answer 4

SELECT userId, AVG(duration)from sessions
GROUP BY userId
HAVING COUNT(userId)>1 ;

Answer 5

Answer is Select * From users Limit 10.