Aggregating using a combination of rows and columns - sql-server

Question

Sample Data from Ranges Table named ranges is shown below:
+-----------------+-------------------+----------+----------+
| SectionCategory | RangeName | LowerEnd | UpperEnd |
+-----------------+-------------------+----------+----------+
| Sanction | 0-7 days | 0 | 7 |
| Sanction | 8-15 days | 8 | 15 |
| Sanction | More than 15 days | 16 | 99999 |
| Disbursal | 0-7 days | 0 | 7 |
| Disbursal | 8-15 days | 8 | 15 |
| Disbursal | More than 15 days | 16 | 99999 |
+-----------------+-------------------+----------+----------+
Sample Data from the Delays Table is shown below:
+-----------+---------------+-----------------+
| Loan No. | SanctionDelay | Disbursal Delay |
+-----------+---------------+-----------------+
| 247 | 8 | 35 |
| 661 | 18 | 37 |
| 1235 | 12 | 6 |
| 1235 | 8 | 15 |
| 1241 | 28 | 9 |
| 1241 | 11 | 9 |
| 1283 | 22 | 20 |
| 1283 | 28 | 41 |
| 1523 | 1 | 27 |
| 1523 | 6 | 28 |
+-----------+---------------+-----------------+
The desired output is shown below:
+-----------+-------------------+-------+
| Section | Range | Count |
+-----------+-------------------+-------+
| Sanction | 0-7 days | 2 |
| Sanction | 8-15 days | 4 |
| Sanction | More than 15 days | 4 |
| Disbursal | 0-7 days | 1 |
| Disbursal | 8-15 days | 3 |
| Disbursal | More than 15 days | 6 |
+-----------+-------------------+-------+
Currently two separate queries are written and UNION is used to collate the output.
From a maintainability point of view, would it be possible to do this in a single query?
(For Sanction in the Ranges table, the SanctionDelay column from Delays Table should be used and for Disbursal, the DisbursalDelay column should be used.) The need is because the number of stages of the loan lifecycle is expected to increase and more and more UNIONs would be needed to collate the output.

Answer 1

It can be done with a CROSS JOIN, not sure how efficient it is.
Sample data:
declare #Ranges table (SectionCategory varchar(10) not null,RangeName varchar(20) not null,LowerEnd int not null,UpperEnd int not null)
insert into #Ranges (SectionCategory,RangeName,LowerEnd,UpperEnd) values
('Sanction','0-7 days',0,7),
('Sanction','8-15 days',8,15),
('Sanction','More than 15 days',16,99999),
('Disbursal','0-7 days',0,7),
('Disbursal','8-15 days',8,15),
('Disbursal','More than 15 days',16,99999)
declare #Delays table (LoanNo int not null,SanctionDelay int not null,DisbursalDelay int not null)
insert into #Delays (LoanNo,SanctionDelay,DisbursalDelay) values
( 247, 8,35),
( 661,18,37),
(1235,12, 6),
(1235, 8,15),
(1241,28, 9),
(1241,11, 9),
(1283,22,20),
(1283,28,41),
(1523, 1,27),
(1523, 6,28)
Query (must be run in same batch as sample data):
select
r.SectionCategory,
r.RangeName,
SUM(CASE
WHEN r.SectionCategory='Sanction' and d.SanctionDelay BETWEEN r.LowerEnd and r.UpperEnd then 1
WHEN r.SectionCategory='Disbursal' and d.DisbursalDelay BETWEEN r.LowerEnd and r.UpperEnd then 1
else 0 end) as Cnt
from #Ranges r
cross join
#Delays d
group by
r.SectionCategory,
r.RangeName
order by SectionCategory,RangeName
Results:
SectionCategory RangeName Cnt
--------------- -------------------- -----------
Disbursal 0-7 days 1
Disbursal 8-15 days 3
Disbursal More than 15 days 6
Sanction 0-7 days 2
Sanction 8-15 days 4
Sanction More than 15 days 4
From a maintainability perspective, it may be better to have a single delay column in the delays table and an additional column that specifies the type of the delay. At the moment, it feels like some form of attribute splitting - in the Ranges table, the type is represented as a column value (Sanction, Disbursal, etc), yet in the delays table, this same "type" is represented in the table meta-data, in terms of distinct column names.
You say that "the number of stages of the loan lifecycle is expected to increase", and I'd expect that this cross over (representing attributes as data in some tables and meta-data in others) will increase the pain of writing decent queries.

Answer 2

Try this
SELECT
SectionCategory
,RangeName
,CASE
WHEN R.SectionCategory='Sanction' THEN
(SELECT COUNT(1) FROM Delays D WHERE D.Sanction_Delay BETWEEN R.LowerEnd AND R.UpperEnd)
WHEN R.SectionCategory='Disbursal' THEN
(SELECT COUNT(1) FROM Delays D WHERE D.[Disbursal Delay] BETWEEN R.LowerEnd AND R.UpperEnd)
END as cnt
FROM Ranges R
Here is SQLFiddle demo