一个数字范围减去另一个数字范围

Question

I have number interval from X to Y (for example x = 100, y = 200, so interval is 100, 101, ... 200) and have table with two columns "from" and "two", wich means another intervals, like

from    to
110    120
130    140

I need to subtract from range (x,y) all ranges in table (from, to). So, the resul will

100 109 
121 129 
141 200

Is it possible?

Answer 1

One way would be ( DEMO )

DECLARE @X INT = 100,
        @Y INT = 200;

WITH N(N)
     AS (SELECT @X
         UNION ALL
         SELECT N + 1
         FROM   N
         WHERE  N < @Y),
     T1
     AS (SELECT N,
                NewGrp = CASE WHEN N = 1 + LAG(N) OVER (ORDER BY N) THEN 0 ELSE 1 END
         FROM   N
         WHERE  NOT EXISTS (SELECT *
                            FROM   #intervals
                            WHERE  N BETWEEN [from] AND [to])),
     T2
     AS (SELECT N,
                Grp = SUM(NewGrp) OVER (ORDER BY N ROWS UNBOUNDED PRECEDING) 
         FROM   T1)
SELECT MIN(N),
       MAX(N)
FROM   T2
GROUP  BY Grp
OPTION (MAXRECURSION 10000) 

You could simplify things and make it a bit more efficient by using a permanent numbers table instead of a recursive CTE