Create a sql view based converting ranges into row

问题:

I have a table structured like so

ColA|ColB|LowRange|HighRange
----------------------------
  1   A     1         5

I would like to create a view that will make the data available in the following format

ColA|ColB|RangeNumber
----------------------
  1   A       1
  1   A       2 
  1   A       3
  1   A       4
  1   A       5

I'm not familiar enough with views so I need some direction.

Thanks

回答1:

You can accomplish this using a recursive CTE

CREATE TABLE ranges (
    ColA int,
    ColB char,
    LowRange int,
    HighRange int,
);

INSERT INTO ranges
VALUES (1, 'A', 1, 5),
(2, 'B', 5, 10);
GO

CREATE VIEW range_view
AS
WITH each AS
(
    SELECT ColA, ColB, LowRange AS n, HighRange
      FROM ranges
    UNION ALL
    SELECT ColA, ColB, n + 1, HighRange
      FROM each
     WHERE n + 1 <= HighRange
)
SELECT ColA, ColB, n
FROM each
GO

SELECT * FROM range_view
DROP VIEW range_view
DROP TABLE ranges;

回答2:

The only way I can figure this one out is by creating a separate table that has all the numbers and then join to the original table. I created a table called 'allnumbs' and it has only one column with the name of 'num' and a record for every number between 1 and 10. Then you join them.

select cola, colb, b.num from temp a
join allnumbs b on b.num >= a.lownum and b.num <= a.highnum

Table temp is your table that your displayed. Hope this helps.