MS SQL - Aging Records - sql

Question

Please help as I am stuck with this!! :/
I have 5 columns that I select in a query and last 2 are derived/calculated
Date | Account | Symbol | Type | User | AgeKEY | Age |
where KEY is concatenated (Account+Symbol+Type+User)
How do I look back 1 year into history and calculate the Age of the record? Age is the continuous # of business days that the AgeKey appears in history
Aging Logic Example -
11/3 KeyExists hence Age = 1
11/4 KeyExists hence Age = 2
11/7 KeyExists hence Age = 3 (note over weekend ages only by 1 day)
11/8 KeyDoesntExist
11/9 KeyExists hence Age = 1 (counter restarts from 1 if this happens)

Answer 1

with T-SQL loop (it reads data from tab table and inserts to tab_result):
create table tab
(dt date, id int);
insert into tab values(DATEADD(day,-12,GETDATE()),1);
insert into tab values(DATEADD(day,-10,GETDATE()),1);
insert into tab values(DATEADD(day,-9,GETDATE()),1);
insert into tab values(DATEADD(day,-8,GETDATE()),1);
insert into tab values(DATEADD(day,-7,GETDATE()),3);
insert into tab values(DATEADD(day,-6,GETDATE()),3);
insert into tab values(DATEADD(day,-5,GETDATE()),1);
insert into tab values(DATEADD(day,-4,GETDATE()),1);
insert into tab values(DATEADD(day,-3,GETDATE()),1);
create table tab_result
(dt date, id int, age int);
DECLARE #id INT, #dt date, #prevId INT=NULL, #prevDt date=NULL, #age int
DECLARE CurName CURSOR FAST_FORWARD READ_ONLY
FOR
SELECT id,dt
FROM tab
ORDER BY id,dt
OPEN CurName
FETCH NEXT FROM CurName INTO #id, #dt
set #age=0;
WHILE ##FETCH_STATUS = 0
BEGIN
if (#prevId<>#id or #prevDt <> DATEADD(day,-1, #dt))
set #age=1;
else
set #age=#age+1;
insert into tab_result values (#dt, #id, #age )
set #prevId=#id
set #prevDt=#dt
FETCH NEXT FROM CurName INTO #id, #dt
END
CLOSE CurName
DEALLOCATE CurName
select * from tab_result order by id, dt;
with plain sql it would be something like below (id in the example is your key):
create table tab
(dt date, id int);
insert into tab values(DATEADD(day,-12,GETDATE()),1);
insert into tab values(DATEADD(day,-10,GETDATE()),1);
insert into tab values(DATEADD(day,-9,GETDATE()),1);
insert into tab values(DATEADD(day,-8,GETDATE()),1);
insert into tab values(DATEADD(day,-7,GETDATE()),3);
insert into tab values(DATEADD(day,-6,GETDATE()),3);
insert into tab values(DATEADD(day,-5,GETDATE()),1);
insert into tab values(DATEADD(day,-4,GETDATE()),1);
insert into tab values(DATEADD(day,-3,GETDATE()),1);
with x as (
select tab.dt,
tab.id,
case when prev.dt is not null then 1 else 0 end as exists_on_prev_day
from
tab left outer join tab prev on (tab.id=prev.id and DATEADD(day,-1 , tab.dt)= prev.dt)
)
select id,dt,
(select
-- count all records with the same id and date less or equal date of the given record
count(*) from x x2 where x2.id=x.id and x2.dt<=x.dt
-- (tricky part) we want to count only records between current record and last record without "previous" record (that is with exists_on_prev_day flag = 0)
and not exists (select 1 from x x3 where x3.id=x2.id and x3.dt>x2.dt and x3.dt<=x.dt and x3.exists_on_prev_day=0 )) age
from x
order by id, dt;
result:
id dt age
1 1 19.11.2016 00:00:00 1
2 1 21.11.2016 00:00:00 1
3 1 22.11.2016 00:00:00 2
4 1 23.11.2016 00:00:00 3
5 1 26.11.2016 00:00:00 1
6 1 27.11.2016 00:00:00 2
7 1 28.11.2016 00:00:00 3
8 3 24.11.2016 00:00:00 1
9 3 25.11.2016 00:00:00 2