SQL - Multiple values to one - sql

Question

Please help me, the question is probably stupid, but I'm at a dead end. There is a table with the following data:
Num
Start number
Date start
111
225
11.11.22
111
223
9.11.22
111
220
9.11.22
222
347
11.11.22
222
345
11.11.22
222
343
10.11.22
I would like to come to something like this, so that Num is displayed in one cell, the first and last values are displayed in the Start number and Date start fields, respectively, and their number is also counted in one cell:
Num
Start number
Date start
Count
111
225
11.11.22
3
220
9.11.22
222
347
11.11.22
3
343
10.11.22

Answer 1

What you want is literally done in this query:
with t(Num, Start_number, Date_start) as (
select 111 , 225 , '11.11.22' from dual union all
select 111 , 223 , '9.11.22' from dual union all
select 111 , 220 , '9.11.22' from dual union all
select 222 , 347 , '11.11.22' from dual union all
select 222 , 345 , '11.11.22' from dual union all
select 222 , 343 , '10.11.22' from dual
)
select case when p.is_first = 1 then p.num end as num
, p.start_number
, p.date_start
, case when p.is_first = 1 then p.cnt end as num
from (
select t.*
, case when start_number = max(start_number) over (partition by num) then 1 else 0 end as is_first
, case when start_number = min(start_number) over (partition by num) then 1 else 0 end as is_last
, count(*) over (partition by num) as cnt
from t
) p
where p.is_first = 1 or p.is_last = 1
fiddle
However I agree with commenters this should be done at GUI level rather than SQL level. It does not make sense to alternate null and nonnull values (is it for some report?). You can utilize the p ("precomputation") subquery anyway, just change outer query then.

Answer 2

You can try the following SQL code:
SELECT
Num,
StartNumber,
DateStart,
[Count]
FROM
(
SELECT
Num,
[Count],
(SELECT MAX(StartNumber) FROM table AS t2 WHERE (t2.Num = t1.Num) AND (t2.DateStart = t1.MaxDateStart)) AS StartNumber,
MaxDateStart AS DateStart
FROM
(
SELECT
Num,
COUNT(*) AS [Count],
MAX(DateStart) AS MaxDateStart
FROM
table
GROUP BY
Num
) AS t1
UNION
SELECT
Num,
[Count],
(SELECT MIN(StartNumber) FROM table AS t2 WHERE (t2.Num = t1.Num) AND (t2.DateStart = t1.MinDateStart)) AS StartNumber,
MinDateStart AS DateStart
FROM
(
SELECT
Num,
COUNT(*) AS [Count],
MIN(DateStart) AS MinDateStart
FROM
table
GROUP BY
Num
) AS t1
) AS t
ORDER BY
Num, DateStart DESC
This code works without OVER for different RDBMS.