abstract:
cursors (used in for loops):
- sql-query to get the result-set is executed one time, to make a result set (in the initialsation-part of procedure)
- one small result-set
- fastest way for a cpu to grap the data, because they are in the ram
ordinary queries (used in for loops):
- executed to get on row per query
- in every execution the whole table has to be scaned to get one row, so there is no result-set to crawl over
- no fast way for the cpu to grap the data, because data is on harddrive
I'm not sure who wrote that for you but it's mostly full of hooie... not all cursors are in ram just like not all non cursors are on disk.
Basically, cursors will always be slower than "Set Based" queries because cursors (and While Loops) override the "natural" way that SQL Server operates.
With only 1 exception in 10,000, you should simply avoid cursors.
--Jeff Moden
Change is inevitable... Change for the better is not.