I have table in Teradata SQL like below:
SMS_ID | CLIENT_ID
-------------------
11 | 123
22 | 123
33 | 123
87 | 456
89 | 456
14 | 888
My question is: How can I calculate in Teradata SQL mean number of SMS per CLIENT ?
If I calculate correctly, mean number of SMS per client im my example is 2 because (3+2+1) / 3 = 2
First aggregate and find the counts for each client, then subquery the and take the average of the entire table.
SELECT AVG(cnt)
FROM
(
SELECT COUNT(*) AS cnt
FROM yourTable
GROUP BY CLIENT_ID
) t;