I want to add a variable number of records in a table (days)
And I've seen a neat solution for this:
SET @nRecords=DATEDIFF(d,'2009-01-01',getdate())
SET ROWCOUNT @nRecords
INSERT int(identity,0,1) INTO #temp FROM sysobjects a,sysobjects b
SET ROWCOUNT 0
But sadly that doesn't work in a UDF (because the #temp and the SET ROWCOUNT). Any idea how this could be achieved?
At the moment I'm doing it with a WHILE and a table variable, but in terms of performance it's not a good solution.
If you're using SQL 2005 or newer, you can use a recursive CTE to get a list of dates or numbers...
with MyCte AS
(select MyCounter = 0
UNION ALL
SELECT MyCounter + 1
FROM MyCte
where MyCounter < DATEDIFF(d,'2009-01-01',getdate()))
select MyCounter, DATEADD(d, MyCounter, '2009-01-01')
from MyCte
option (maxrecursion 0)
/* output...
MyCounter MyDate
----------- -----------------------
0 2009-01-01 00:00:00.000
1 2009-01-02 00:00:00.000
2 2009-01-03 00:00:00.000
3 2009-01-04 00:00:00.000
4 2009-01-05 00:00:00.000
5 2009-01-06 00:00:00.000
....
170 2009-06-20 00:00:00.000
171 2009-06-21 00:00:00.000
172 2009-06-22 00:00:00.000
173 2009-06-23 00:00:00.000
174 2009-06-24 00:00:00.000
(175 row(s) affected)
*/
You can use a WHILE statement for that:
declare @i int
declare @rows_to_insert int
set @i = 0
set @rows_to_insert = 1000
while @i < @rows_to_insert
begin
INSERT INTO #temp VALUES (@i)
set @i = @i + 1
end
this is the approach I'm using and works best for my purposes and using SQL 2000. Because in my case is inside an UDF, I can't use ## or # temporary tables so I use a table variable. I'm doing:
DECLARE @tblRows TABLE (pos int identity(0,1), num int)
DECLARE @numRows int,@i int
SET @numRows = DATEDIFF(dd,@start,@end) + 1
SET @i=1
WHILE @i<@numRows
begin
INSERT @tblRows SELECT TOP 1 1 FROM sysobjects a
SET @i=@i+1
end
Overall much faster to double the amount of rows at every iteration
CREATE TABLE dbo.Numbers(n INT NOT NULL PRIMARY KEY)
GO
DECLARE @i INT;
SET @i = 1;
INSERT INTO dbo.Numbers(n) SELECT 1;
WHILE @i<128000 BEGIN
INSERT INTO dbo.Numbers(n)
SELECT n + @i FROM dbo.Numbers;
SET @i = @i * 2;
END;
I deliberately did not SET NOCOUNT ON, so that you see how it inserts 1,2,4,8 rows
you can use a cross join
select top 100000 row_number() over(order by t1.number)-- here you can change 100000 to a number you want or a variable
from master.dbo.spt_values t1
cross join master.dbo.spt_values t2
When you have a pre-built numbers table, just use that:
SELECT *
FROM numbers
WHERE number <= DATEDIFF(d,'2009-01-01',getdate())
There are any number of techniques for building the numbers table in the first place (using techniques here), but once it's built and indexed, you don't build it again.
You could do what PinalDave suggests:
INSERT INTO MyTable (FirstCol, SecondCol)
SELECT 'First' ,1
UNION ALL
SELECT 'Second' ,2
UNION ALL
SELECT 'Third' ,3
UNION ALL
SELECT 'Fourth' ,4
UNION ALL
SELECT 'Fifth' ,5
GO
How about:
DECLARE @nRecords INT
SET @nRecords=DATEDIFF(d,'2009-01-01',getdate())
SELECT TOP (@nRecords)
ROW_NUMBER() OVER (ORDER BY a.object_id, b.object_id) - 1
FROM sys.objects a, sys.objects b
If you don't want it zero-indexed, remove the " - 1
"
Requires at least SQL Server 2005.
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