Getting aggregate data in MySql - google-bigquery

Question

I am attempting to write a sql query to fetch aggregate data from a table. I have a table with data that looks as follows (example data):
trackingId
numberOfRecords
totalRecords
dateSubmitted
fileName
checkpoint
status
1
10
100
01/01/2021
example.doc
gateway
in-progress
1
20
100
02/01/2021
null
checkpoint1
in-progress
1
20
100
03/01/2021
null
checkpoint2
in-progress
The aggregate data I would like to query would look like:
trackingId
numberOfRecords
totalRecords
dateSubmitted
fileName
checkpoint
status
1
50
100
03/01/2021
example.doc
checkpoint2
in-progress
In summary, I would like to:
group on trackingId (done)
Sum of all records fetched (done)
get the latest date (done)
name of original document (not sure how to fetch a value from the first row only, I am trying to avoid subqueries due to inefficiencies)
latest checkpoint (get value from the newest record)
latest status (get value from the newest record)
My issue mainly is fetching specific data from either the newest or oldest record.
Thanks.

Answer 1

Consider below
select trackingId,
sum(numberOfRecords) as numberOfRecords,
any_value(totalRecords) as totalRecords,
max(dateSubmitted) as dateSubmitted,
array_agg(fileName order by dateSubmitted limit 1)[offset(0)] as fileName,
array_agg(checkpoint order by dateSubmitted desc limit 1)[offset(0)] as checkpoint,
array_agg(status order by dateSubmitted desc limit 1)[offset(0)] as status,
from `project.dataset.table`
group by trackingId
if applied to sample data in your question - output is

Answer 2

Look for this:
CREATE TABLE test ( id INT, -- will be used for ordering
cat INT, -- will be used for aggregation
col1 INT, -- will be used for to get SUM
col2 INT, -- will be used for to get value from 1st row
col3 INT -- will be used for to get value from last row
);
INSERT INTO test VALUES
(1,1,11,111,1111), (2,1,22,222,2222), (3,1,33,333,3333),
(4,2,4,4,4), (5,2,5,5,5);
SELECT * FROM test;
id
cat
col1
col2
col3
1
1
11
111
1111
2
1
22
222
2222
3
1
33
333
3333
4
2
4
4
4
5
2
5
5
5
SELECT cat,
SUM(col1) col1_sum,
SUBSTRING_INDEX(GROUP_CONCAT(col2 ORDER BY id), ',', 1) col2_first,
SUBSTRING_INDEX(GROUP_CONCAT(col3 ORDER BY id), ',', -1) col3_last
FROM test
GROUP BY cat;
cat
col1_sum
col2_first
col3_last
1
66
111
3333
2
9
4
5
db<>fiddle here
The values processed by GROUP_CONCAT() must have no comma in the value.
PS. Do not forget about group_concat_max_len, especially when single value in the column may be long.
PPS. The expression for last value may be SUBSTRING_INDEX(GROUP_CONCAT(col3 ORDER BY id DESC), ',', 1) col3_last.