Question

I’m trying to select some traffic flow data and create sums for the different traffic directions, bucketed in 60 second buckets. Simplified table is below (timestamp is unix epoch):

Timestamp      Source     Destination    Count
1              inside     outside          5
2              inside     outside          6
3              outside    inside           7
65             inside     inside           4
66             inside     outside          6
72             inside     outside          7

Current Query (which does the bucketing, but doesn’t have anything about direction)

SELECT sum(count) AS total FROM table GROUP BY round(timestamp/60)

This gives me the total count for each 60 second “bucket” like

Count
 18
 10
 7

Now, where I’m lost (I can do this in the client code, but I’d kinda like to do it with the SQL if possible). I’d like to have a sum called inbound for every row with inside as source and dest as outside, a sum called outbound for every row with outside in source and inside as dest, and a row called internal where both source and dest are inside. Still grouped by the 60 second bucket. i.e. what I want back is:

Inbound  Outbound  Internal
   7        11        0
   0         6        4
   0         7        0

My SQL foo is weak, and I really don’t know where to start (I suspect I need a subselect, but I’m not sure how to construct it).

Answer 1

You should actually be able to do a pivot:

SELECT SUM(count) AS total
    , SUM(CASE 
              WHEN Source = 'outside' 
                   AND Destination = 'inside' 
                   THEN count  -- Use 1 if you only want to count each row
              ELSE 0 END) AS [Inbound]
    , SUM(CASE
              WHEN Source = 'inside' 
                  AND Destination = 'outside' 
                  THEN count
              ELSE 0 END) AS [Outbound]
    , SUM(CASE 
              WHEN Source = 'inside'
                  AND Destination = 'inside' 
                  THEN count
              ELSE 0 END) AS [Internal]
FROM table 
GROUP BY round(timestamp/60)