Dynamically create ranges from numeric sequences - sql

Question

I have a table like the following:
+----+-----+-----+
| ID | GRP | NR |
+----+-----+-----+
| 1 | 1 | 101 |
| 2 | 1 | 102 |
| 3 | 1 | 103 |
| 4 | 1 | 105 |
| 5 | 1-2 | 106 |
| 6 | 1-2 | 109 |
| 7 | 1-2 | 110 |
| 8 | 2 | 201 |
| 9 | 2 | 202 |
| 10 | 3 | 300 |
| 11 | 3 | 350 |
| 12 | 3 | 351 |
| 13 | 3 | 352 |
+----+-----+-----+
I wanted to create a view which groups this list by GRP and concatenates values in NR.
Is it possible to dynamically detect sequences and shorten them into ranges?
Like 1, 2, 3, 5 would become 1-3, 5.
So the result should look like this:
+-----+--------------------+
| GRP | NRS |
+-----+--------------------+
| 1 | 101 - 103, 105 |
| 1-2 | 106, 109 - 110 |
| 2 | 201 - 202 |
| 3 | 300, 350 - 352 |
+-----+--------------------+
What i got now is simply concatenate values, so the table above would become this:
+-----+--------------------+
| GRP | NRS |
+-----+--------------------+
| 1 | 101, 102, 103, 105 |
| 1-2 | 106, 109, 110 |
| 2 | 201, 202 |
| 3 | 300, 350, 351, 352 |
+-----+--------------------+
Here's the actual statement:
DECLARE #T TABLE
(
ID INT IDENTITY(1, 1)
, GRP VARCHAR(10)
, NR INT
)
INSERT INTO #T
VALUES ('1',101),('1',102),('1',103),('1',105)
,('1-2',106),('1-2',109), ('1-2',110)
,('2',201),('2',202)
,('3',300),('3',350),('3',351),('3',352)
SELECT * FROM #T
;WITH GROUPNUMS (RN, GRP, NR, NRS) AS
(
SELECT 1, GRP, MIN(NR), CAST(MIN(NR) AS VARCHAR(MAX))
FROM #T
GROUP BY GRP
UNION ALL
SELECT CT.RN + 1, T.GRP, T.NR, CT.NRS + ', ' + CAST(T.NR AS VARCHAR(MAX))
FROM #T T
INNER JOIN GROUPNUMS CT ON CT.GRP = T.GRP
WHERE T.NR > CT.NR
)
SELECT NRS.GRP, NRS.NRS
FROM GROUPNUMS NRS
INNER JOIN (
SELECT GRP, MAX(RN) AS MRN
FROM GROUPNUMS
GROUP BY GRP
) R
ON NRS.RN = R.MRN AND NRS.GRP = R.GRP
ORDER BY NRS.GRP
Can anyone tell me if it's easily possible to do something like that?
Would be great if anyone has an idea and would like to share it.

Answer 1

SQLFiddle demo
with TRes
as
(
select T.GRP,T.NR NR,
CASE WHEN T1.NR IS NULL and T2.NR is null
THEN CAST(T.NR as VARCHAR(MAX))
WHEN T1.NR IS NULL and T2.NR IS NOT NULL
THEN '-'+CAST(T.NR as VARCHAR(MAX))
WHEN T1.NR IS NOT NULL and T2.NR IS NULL
THEN CAST(T.NR as VARCHAR(MAX))+'-'
END AS NR_GRP
from T
left join T T1 on T.Grp=T1.Grp and t.Nr+1=t1.Nr
left join T T2 on T.Grp=T2.Grp and t.Nr-1=t2.Nr
WHERE T1.NR IS NULL or T2.NR IS NULL
)
SELECT
GRP,
REPLACE(
substring((SELECT ( ',' + NR_GRP)
FROM TRes t2
WHERE t1.GRP = t2.GRP
ORDER BY
GRP,
NR
FOR XML PATH( '' )
), 2, 10000 )
,'-,-','-')
FROM TRes t1
GROUP BY GRP

Answer 2

Please check my try:
DECLARE #T TABLE
(
ID INT IDENTITY(1, 1)
, GRP VARCHAR(10)
, NR INT
)
INSERT INTO #T
VALUES ('1',101),('1',102),('1',103),('1',105)
,('1-2',106),('1-2',109), ('1-2',110)
,('2',201),('2',202)
,('3',300),('3',350),('3',351),('3',352)
SELECT * FROM #T
;WITH T1 as
(
SELECT GRP, NR, ROW_NUMBER() over(order by GRP, NR) ID FROM #T
)
,T as (
SELECT *, 1 CNT FROM T1 where ID=1
union all
SELECT b.*, (case when T.NR+1=b.NR and T.GRP=b.GRP then t.CNT
else T.CNT+1 end)
from T1 b INNER JOIN T on b.ID=T.ID+1
)
, TN as(
select *,
MIN(NR) over(partition by GRP, CNT) MinVal,
MAX(NR) over(partition by GRP, CNT) MaxVal
From T
)
SELECT GRP, STUFF(
(SELECT distinct ','+(CASE WHEN MinVal=MaxVal THEN CAST(MinVal as nvarchar(10)) ELSE CAST(MinVal as nvarchar(10))+'-'+cast(MaxVal as nvarchar(10)) END)
FROM TN b where b.GRP=a.GRP
FOR XML PATH(''),type).value('.','nvarchar(max)'),1,1,'') AS [ACCOUNT NAMES]
FROM TN a GROUP BY GRP