Question

Here’s the situation. I created a view that has all the following information

CREATE VIEW view2 AS
SELECT activity_id,
       subject_code,
       academic_period_code,
       DATEDIFF(HOUR,time_start,time_end) AS duration
FROM   activity

Okay, now I’m trying to make a query that can produce two columns,
1. one with subject code and the academic_period code concatenated into one column
2. The second column contains the total number of duration for each subject that is in that academic period

So its like: CS123 in academic_period 121 has total of 5 hours activity. I’m fine with the first column but I’ve been wondering how do I get the 2nd column. If I use the SUM function it just totals up the column itself so I’m not sure how to deal with this.

Sample data

Subject Code   Activity_code    Academic_Period_Code   Duration
CS123          1                 121                   2
CS123          2                 121                   3
CS123          3                 122                   2
CS123          4                 122                   2

What I have done?]

SELECT subject_code + academic_period_code AS subject,
       (I think I have to do a subquery but I'm not sure how its suppose to work out) AS total_activity_time

FROM view2

Answer 1

Assuming SQL Server and that I understand what you are looking for:

select
    subject_code + academic_period_code as [Type],
    sum(duration) as duration
from view2
group by
    subject_code + academic_period_code;

should get you where I think you’re trying to get.