Basic Cursor and Loop usage with examples

This is a basic cursor, useful for smaller amounts of data.  It enables you to carry out a query against each record independantly before moving on to the next one. 

declare @Parameter1 varchar(50)

declare @Parameter2 varchar(50)

declare cur_cursor cursor for (select fieldname1,fieldname2
                                                           from server.[database].[dbo].[table with data])

open cur_cursor

Fetch Next from cur_cursor into @Parameter1, @Parameter2

While @@fetch_status = 0

begin

update table
set fieldname = @Parameter1
where otherfieldname = @Parameter2

Fetch Next from cur_cursor into @Parameter1, @Parameter2

end
close cur_cursor
deallocate cur_cursor

The following cursor uses dynamic SQL, which can allow you to add columns to a table, or deduce which columns you wish to query. 
declare @Parameter1 varchar(50)

declare @Parameter2 varchar(50)

declare @SQL nvarchar(4000)

declare cur_cursor cursor for (select fieldname1,fieldname2

                              from server.[database].[dbo].[table with data])

open cur_cursor

Fetch Next from cur_cursor into @Parameter1, @Parameter2

While @@fetch_status = 0

begin

set @SQL = 'update tablename

                set fieldname = ''test' + @Parameter2 + '''
           where otherfield = ''' + @Parameter1 + ''''

exec sp_execute @SQL

Fetch Next from cur_cursor into @Parameter1, @Parameter2

end

close cur_cursor
deallocate cur_cursor

There will be more to follow with more detailed explanations, examples of loops for larger datasets and nested loops, after the weekend.


Any questions let me know.