Ok, I'm certainly familiar with walking through a table using a read-only cursor, but I can't seem to find the right syntax for actually updating the current row (Neither the cursor page nor the UPDATE page in books online seems to show this simple operation):
DECLARE @counter int;
SET @counter = 1;
DECLARE myCursor CURSOR FOR
SELECT RowID, Value FROM myTable
FOR UPDATE OF Value;
OPEN myCursor;
WHILE @counter < 100
FETCH NEXT FROM myCursor
UPDATE myCursor SET Value = @Counter << DOESN'T WORK
SET @counter = @counter + 1
END
CLOSE myCursor
DEALLOCATE myCursor
I also tried just SET Value = @Counter
and using an INTO @Value
on the FETCH, but couldn't seem to get that to work either.
This is obviously over-simplified, there are much more efficient ways to just "count" down a column. I won't bore you with the actual calculation.
Yes, I do need a cursor and not an UPDATE on the entire table (t开发者_Go百科he value for each successive row will be based on a calculation that depends on the prior row already being written).
Testing this initially on SQL 2005, but I will need to port the code to SQL 2000 and 2008 as well. Thanks!
You want to use WHERE CURRENT OF
-
DECLARE complex_cursor CURSOR FOR
SELECT a.BusinessEntityID
FROM HumanResources.EmployeePayHistory AS a
WHERE RateChangeDate <>
(SELECT MAX(RateChangeDate)
FROM HumanResources.EmployeePayHistory AS b
WHERE a.BusinessEntityID = b.BusinessEntityID) ;
OPEN complex_cursor;
FETCH FROM complex_cursor;
UPDATE HumanResources.EmployeePayHistory
SET PayFrequency = 2
WHERE CURRENT OF complex_cursor;
CLOSE complex_cursor;
DEALLOCATE complex_cursor;
GO
That is from MSDN.
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