I need to do a function where I read one by one the records of a query like: select * from alumnos
to be able to use the data one at a time, and to modify them one at a time.
Therefore the idea was to put it in a while and go modifying them but I do not know how to go selecting one by one and without repeating them. All this in SQL 2008 language
This would be an example of what you need to do, a cursor that traverses the tuples and a loop to iterate through them and do what you need
SET NOCOUNT ON;
DECLARE @vendor_id int, @vendor_name nvarchar(50),
@message varchar(80), @product nvarchar(50);
PRINT '-------- Vendor Products Report --------';
DECLARE vendor_cursor CURSOR FOR SELECT VendorID, Name FROM Purchasing.Vendor WHERE PreferredVendorStatus = 1 ORDER BY VendorID;
OPEN vendor_cursor
FETCH NEXT FROM vendor_cursor INTO @vendor_id, @vendor_name
WHILE @@FETCH_STATUS = 0 BEGIN
PRINT ' '
SELECT @message = '----- Products From Vendor: ' +
@vendor_name
PRINT @message
-- Declare an inner cursor based
-- on vendor_id from the outer cursor.
DECLARE product_cursor CURSOR FOR
SELECT v.Name
FROM Purchasing.ProductVendor pv, Production.Product v
WHERE pv.ProductID = v.ProductID AND
pv.VendorID = @vendor_id -- Variable value from the outer cursor
OPEN product_cursor
FETCH NEXT FROM product_cursor INTO @product
IF @@FETCH_STATUS <> 0
PRINT ' <<None>>'
WHILE @@FETCH_STATUS = 0
BEGIN
SELECT @message = ' ' + @product
PRINT @message
FETCH NEXT FROM product_cursor INTO @product
END
CLOSE product_cursor
DEALLOCATE product_cursor
-- Get the next vendor.
FETCH NEXT FROM vendor_cursor
INTO @vendor_id, @vendor_name END CLOSE vendor_cursor; DEALLOCATE vendor_cursor;
If it's how I'm thinking, it would be grouping the select by the fields contained in the table and in that way the data is not repeated:
Select Codest,Nombre,Apellido from estudiantes
group by Codest,Nombre,Apellido
And with the application, of the language that is, you get that information and with a cycle (as you like) in the datatable or dataset you will edit each one of the records that you have.