SQL Server - List single row multiple times in query result - sql

Question

I have a dataset in a SQL Server database, and I'd like to list run a query to list records from a table, multiple times according to the respective integer value in a column of that table.
I've seen many of the posts about listing a record multiple times in a query, with most of the more suitable responses describing a solution involving Cross join. The situation I'm describing is slightly different from what I've seen of yet, however.
The table structure of the records is akin to the following:
+-----+-------+------+------+
| id | name | type | num |
+-----+-------+------+------+
| 1 | bob | red | 1 |
+-----+-------+------+------+
| 2 | sam | blue | 3 |
+-----+-------+------+------+
| 3 | viv | green| 2 |
+-----+-------+------+------+
I'd like to display this in a query result as follows...
+-----+-------+------+
| id | name | type |
+-----+-------+------+
| 1 | bob | red |
+-----+-------+------+
| 2 | sam | blue |
+-----+-------+------+
| 2 | sam | blue |
+-----+-------+------+
| 2 | sam | blue |
+-----+-------+------+
| 3 | viv | green|
+-----+-------+------+
| 3 | viv | green|
+-----+-------+------+
... where each record appears multiple times according to the number it is listed in the original row. (bob * 1, sam * 3, viv * 2)
Is this possible via cross-join or any other method available?
Note: This does not need to be terribly efficient.

Answer 1

You can try to use recursive CTE
;with cte as (
SELECT id,name,type,1 startnum,num
FROM T
UNION ALL
SELECT id,name,type , startnum+1,num
FROM cte
WHERE startnum+1<=num
)
SELECT id,name,type
FROM cte
order by id
sqlfiddle

Answer 2

Another option is an ad-hoc tally/numbers table
Example
Select A.ID
,A.[Name]
,A.[Type]
From YourTable A
Cross Apply (Select Top (A.[num]) N=Row_Number() Over (Order By (Select NULL)) From master..spt_values n1) B
Or a simple JOIN
Select A.ID
,A.[Name]
,A.[Type]
From YourTable A
Join (Select Top (100) N=Row_Number() Over (Order By (Select NULL)) From master..spt_values n1) B
on B.N<=A.[Num]
Both would Return
ID Name Type
1 bob red
2 sam blue
2 sam blue
2 sam blue
3 viv green
3 viv green

Answer 3

Use a Stored procedure
create a temporary table variable
Write insert into temporary table in a while loop
while counter < max(num)
insert into table where counter <=num
Finally select from table .

Answer 4

EDITED:
(Thanks, #MatBailie!)
Using a recursive CTE on the num column to generate the required number of repetitions, and doing a left-join:
Given table so1 as follows:
id name type num
1 bob red 1
2 sam blue 3
3 viv green 2
4 jon grey 7
Try:
WITH RECURSIVE exp_num AS
(
SELECT id, num FROM so1
UNION
SELECT id, num - 1 FROM exp_num WHERE num > 1
)
SELECT s1.* FROM so1 s1
LEFT JOIN
(
SELECT id FROM exp_num
) s2
ON s1.id = s2.id
Output:
id name type
1 bob red
2 sam blue
2 sam blue
2 sam blue
3 viv green
3 viv green
4 jon grey
4 jon grey
4 jon grey
4 jon grey
4 jon grey
4 jon grey
4 jon grey