Run insert statement x number of times - tsql

Question

I have two tables. One table A has n rows of data and the other table B is empty. I want to insert n rows into table B, 1 row for each row in table A. Table B will have a couple of fields from table A in it, including a foreign key from table A.
In the end I want one row in B for each row in A. To do this I used:
INSERT INTO B(Col1
,Col2
,Col3
,Col4
,Col5
);
SELECT 100
,25
,'ABC'
,1
,A.ID
FROM Auctions A
Now, I've put this code in a stored procedure and this SP takes an int param called NumInserts.
I want to insert n * NumInserts rows. So, if n is 10 and NumInserts is 5 I want to run this code 5 * 10 (50) times.
In other words for each row in table A I want to insert 5 rows in table B. How would I do that?

Answer 1

create procedure insert_into_b
#numInserts int
as
begin
while #numInserts > 0
begin
insert into b (id)
select id from a
set #numInserts = #numInserts - 1
end
end
exec insert_into_b 2

Answer 2

This is a hack and I wouldn't recommend using it in production or big volumes of data. However, in development quick-and-dirty scenarios I found it often useful:
Use GO \[count\] to execute a batch of commands a specified number of times.
Concretely, if you had a stored procedure called InsertAIntoB, you could run this in Management Studio:
exec InsertAIntoB
GO 10
(replace 10 with whatever NumInserts is)

Answer 3

I prefer to avoid looping when I can, just so I don't have to maintain some easily breakable and somewhat ugly loop structure in my stored procedure.
You could easily do this with a Numbers table, the CROSS APPLY statement, and your existing INSERT statement.
Given that your numbers table would look like this:
Number
======
0
1
2
...
Your SQL statement simply becomes:
INSERT INTO B
(
[Col1]
,[Col2]
,[Col3]
,[Col4]
,[Col5]
)
SELECT
100
,25
,'ABC'
,1
,a.ID
FROM
Auctions a
CROSS APPLY
Numbers n
WHERE
n.Number BETWEEN 1 AND #NumInserts
Numbers tables can be useful if use appropriately. If you're unfamiliar with them, here are a few resources and some pros/cons:
http://dataeducation.com/you-require-a-numbers-table/ (the code to create a numbers table in this article is shown below)
http://archive.msdn.microsoft.com/SQLExamples/Wiki/View.aspx?title=NumbersTable
https://dba.stackexchange.com/questions/11506/why-are-numbers-tables-invaluable
Maybe this solution is overkill if #NumInserts is always going to be a reasonably small number, but if you already have a Numbers table sitting around, you might as well take advantage of it!
UPDATE:
Here's a quick and dirty method to populate a numbers table from 0 to 65,535:
CREATE TABLE Numbers
(
Number INT NOT NULL,
CONSTRAINT PK_Numbers
PRIMARY KEY CLUSTERED (Number)
WITH FILLFACTOR = 100
)
GO
INSERT INTO Numbers
SELECT
(a.Number * 256) + b.Number AS Number
FROM
(
SELECT number
FROM master..spt_values
WHERE
type = 'P'
AND number <= 255
) a (Number),
(
SELECT number
FROM master..spt_values
WHERE
type = 'P'
AND number <= 255
) b (Number)
GO
Credit: http://dataeducation.com/you-require-a-numbers-table/

Answer 4

Create procedure DoitNTimes
#N integer = 1
As
Set NoCount On
While #N > 0 Begin
Insert B (Col1, Col2, Col3, Col4, Col5)
Select 100, 25, 'ABC', 1, A.ID
From Auctions A
-- -----------------------------------
Set #N -= 1
End
If using SQL Server 2005 or earlier replace the Set #N -= 1' withSet #N = #N-1`
and if you really want to avoid loop using T-SQL variables, then use a CTE, not a disk-based table:
Create procedure DoitNTimes
#N integer = 1
As
Set NoCount On
With nums(num) As
(Select #N Union All
Select num - 1
From nums
Where num > 1)
Insert B (Col1, Col2, Col3, Col4, Col5)
Select 100, 25, 'ABC', 1, A.ID
From Auctions A Full Join nums
Option(MaxRecursion 10000)
but of course, this is also still looping, just like any solution to this issue.

Answer 5

Very late answer but there is no need to loop and it's a little simpler than Corey's good answer;
DECLARE #n int = 10;
INSERT INTO B(Col1,Col2,Col3,Col4,Col5);
SELECT 100,25,'ABC',1,A.ID
FROM Auctions A
JOIN (SELECT TOP(#n) 1 [junk] FROM sys.all_objects) as copies ON 1 = 1
You could use any table in the join as long as it has the number of rows you'll need. You could also change "1 [junk]" to "ROW_NUMBER() OVER(ORDER BY object_id) [copyno]" if you wanted a copy number somewhere in the insert table.
Hopefully this will save someone a little work down the road...

Answer 6

Try this (on SQL server databases):
DECLARE #NumInserts SMALLINT = 3
INSERT INTO B (Col1, Col2, Col3, Col4, Col5)
SELECT 100, 25, 'ABC', 1, A.ID
FROM Auctions A
JOIN master.dbo.spt_values numbers ON numbers.number < #NumInserts
WHERE numbers.[type] = 'P'
Note: This will only work if #NumInserts is less than or equal to 2048
master.dbo.spt_values WHERE type = 'P' is just a built-in SQL Server table of numbers from 0 to 2047