Merging data in a single SQL table without a Cursor

Question

I have a table with an ID column and another column with a number. One ID can have multiple numbers. For example

ID | Number
 1 |  25
 1 |  26
 1 |  30
 1 |  24
         


        

Answer 1

Solution with CTE and recursion:

WITH CTE AS (
  SELECT T.ID, T.NUMBER, T.NUMBER AS GRP
  FROM T 
  LEFT OUTER JOIN T T2 ON T.ID = T2.ID AND T.NUMBER -1 = T2.NUMBER 
  WHERE T2.ID IS NULL
  UNION  ALL
  SELECT T.ID, T.NUMBER, GRP
  FROM CTE 
  INNER JOIN T
  ON T.ID = CTE.ID AND T.NUMBER  = CTE.NUMBER + 1
)
SELECT ID, MAX( NUMBER ), MIN(NUMBER)
FROM CTE
GROUP BY ID, GRP

Results at fiddlesql