Group close numbers

Question

I have a table with 2 columns of integers. The first column represents start index and the second column represents end index.

START END
1     8
9     13
14    2         


        

Answer 1

Edited to include another version which i think is a bit more reliable, and also works with overlapping ranges

CREATE TABLE #data (start_range INT, end_range INT)
INSERT INTO #data VALUES (1,8) 
INSERT INTO #data VALUES (2,15) 
INSERT INTO #data VALUES (9,13)
INSERT INTO #data VALUES (14,20) 
INSERT INTO #data VALUES (13,26) 
INSERT INTO #data VALUES (12,21) 
INSERT INTO #data VALUES (9,25) 
INSERT INTO #data VALUES (20,25) 
INSERT INTO #data VALUES (30,42) 
INSERT INTO #data VALUES (42,49) 
INSERT INTO #data VALUES (60,67)   

;with ranges as
(
SELECT start_range as level
,end_range as end_range
,row_number() OVER (PARTITION BY (SELECT NULL) ORDER BY start_range) as row
FROM #data
UNION ALL
SELECT
level + 1 as level
,end_range as end_range
,row
From ranges 
WHERE level < end_range
)
,ranges2 AS
(
SELECT DISTINCT 
level
FROM ranges
)
,ranges3 AS
(
SELECT 
level
,row_number() OVER (ORDER BY level) - level as grouping_group
from ranges2
)
SELECT 
MIN(level) as start_number
,MAX(level) as end_number
FROM ranges3
GROUP BY grouping_group
ORDER BY start_number ASC

---

I think this should work - might not be especially efficient on larger sets though...

CREATE TABLE #data (start_range INT, end_range INT)
INSERT INTO #data VALUES (1,8)
INSERT INTO #data VALUES (2,15)
INSERT INTO #data VALUES (9,13)
INSERT INTO #data VALUES (14,20)
INSERT INTO #data VALUES (21,25)
INSERT INTO #data VALUES (30,42)
INSERT INTO #data VALUES (42,49)
INSERT INTO #data VALUES (60,67)


;with overlaps as
(
select * 
,end_range - start_range as range
,row_number() OVER (PARTITION BY (SELECT NULL) ORDER BY start_range ASC) as line_number
from #data
)
,overlaps2 AS
(
SELECT
O1.start_range
,O1.end_range
,O1.line_number
,O1.range
,O2.start_range as next_range
,CASE WHEN O2.start_range - O1.end_range < 2 THEN 1 ELSE 0 END as overlap
,O1.line_number - DENSE_RANK() OVER (PARTITION BY (CASE WHEN O2.start_range - O1.end_range < 2 THEN 1 ELSE 0 END) ORDER BY O1.line_number ASC) as overlap_group
FROM overlaps O1
LEFT OUTER JOIN overlaps O2 on O2.line_number = O1.line_number + 1
)
SELECT 
MIN(start_range) as range_start
,MAX(end_range) as range_end
,MAX(end_range) - MIN(start_range) as range_span
FROM overlaps2
GROUP BY overlap_group