Update table with new value for each row - sql

Question

I need to update a column (type of datetime) in the top 1000 rows my table. However the catch is with each additional row I must increment the GETDATE() by 1 second... something like DATEADD(ss,1,GETDATE())
The only way I know how to do this is something like this:
UPDATE tablename
SET columnname = CASE id
WHEN 1 THEN DATEADD(ss,1,GETDATE())
WHEN 2 THEN DATEADD(ss,2,GETDATE())
...
END
Obviously this is not plausible. Any ideas?

Answer 1

How about using id rather than a constant?
UPDATE tablename
SET columnname = DATEADD(second, id, GETDATE() )
WHERE id <= 1000;
If you want the first 1000 rows (by id), but the id has gaps or other problems, then you can use a CTE:
with toupdate as (
select t.*, row_number() over (order by id) as seqnum
from tablename
)
update toupdate
set columnname = dateadd(second, seqnum, getdate())
where seqnum <= 1000;

Answer 2

I don't know what your ID is like, and I'm assuming you have at least SQL Server 2008 or else ROW_NUMBER() won't work.
Note: I did top 2 to show you that you that the top works. You can change it to top 1000 for your actual query.
DECLARE #table TABLE (ID int, columnName DATETIME);
INSERT INTO #table(ID)
VALUES(1),(2),(3);
UPDATE #table
SET columnName = DATEADD(SECOND,B.row_num,GETDATE())
FROM #table A
INNER JOIN
(
SELECT TOP 2 *, ROW_NUMBER() OVER (ORDER BY ID) row_num
FROM #table
ORDER BY ID
) B
ON A.ID = B.ID
SELECT *
FROM #table
Results:
ID columnName
----------- -----------------------
1 2015-03-31 13:11:59.760
2 2015-03-31 13:12:00.760
3 NULL

Answer 3

You don't make explicit the SQL Server version you're using, so I will assume SQL Server 2005 or above. I believe the WAITFOR DELAY command would be a good option to keep adding 1 second to each rows of the datetime column.
See this example:
-- Create temp table
CREATE TABLE #Client
(
RecordID int identity(1,1),
[Name] nvarchar(100) not null,
PurchaseDate datetime null
)
-- Fill in temp table with example values
INSERT INTO #Client
VALUES ( 'Jhon', NULL)
INSERT INTO #Client
VALUES ( 'Martha', NULL)
INSERT INTO #Client
VALUES ( 'Jimmy', NULL)
-- Create local variables
DECLARE #currentRecordId int,
#currentName nvarchar(100)
-- Create cursor
DECLARE ClientsCursor CURSOR FOR
SELECT RecordID,
[Name]
FROM #Client
OPEN ClientsCursor
FETCH FROM ClientsCursor INTO #currentRecordId, #currentName
-- Check ##FETCH_STATUS to see if there are any more rows to fetch.
WHILE ##FETCH_STATUS = 0
BEGIN
UPDATE #Client
SET PurchaseDate = DATEADD(ss,1,GETDATE())
WHERE RecordID = #currentRecordId
AND [Name] = #currentName
WAITFOR DELAY '00:00:01.000'
FETCH NEXT FROM ClientsCursor INTO #currentRecordId, #currentName
END
CLOSE ClientsCursor;
DEALLOCATE ClientsCursor;
SELECT *
FROM #Client
And here's the result:
1 Jhon 2015-03-31 15:20:04.477
2 Martha 2015-03-31 15:20:05.473
3 Jimmy 2015-03-31 15:20:06.470
Hope you find this answer helpful

Answer 4

This should be what you need (at least a guidline)
DELIMITER $$
CREATE PROCEDURE ADDTIME()
BEGIN
DECLARE i INT Default 1 ;
simple_loop: LOOP
UPDATE tablename SET columnname = DATE_ADD(NOW(), INTERVAL i SECOND) where rownumber = i
SET i=i+1;
IF i=1001 THEN
LEAVE simple_loop;
END IF;
END LOOP simple_loop;
END $$
To call that stored procedure use
CALL ADDTIME()