Pros and cons of using a cursor (in SQL server)

Question

I asked a question here Using cursor in OLTP databases (SQL server)

where people responded saying cursors should never be used.

I feel cursors are very powerful

Answer 1

The issue with cursors in SQL Server is that the engine is set-based internally, unlike other DBMS's like Oracle which are cursor-based internally. This means that when you create a cursor in SQL Server, temporary storage needs to be created and the set-based resultset needs to be copied over to the temporary cursor storage. You can see why this would be expensive right off the bat, not to mention any row-by-row processing that you might be doing on top of the cursor itself. The bottom line is that set-based processing is more efficient, and often times your cursor-based operation can be done better using a CTE or temp table.

That being said, there are cases where a cursor is probably acceptable, as you said for one-off operations. The most common use I can think of is in a maintenance plan where you may be iterating through all the databases on a server executing various maintenance tasks. As long as you limit your usage and don't design whole applications around RBAR (row-by-agonizing-row) processing, you should be fine.