curcers and pl/sql?

Question

i've understood that it's only some nested select statement

since we say SELECT FETCH

but i did not acually get it why we need them

Answer 1

If you are talking Oracle PL/SQL they are really useful inside packages.

The cursor basically brings back the data set that you can then use programatically to make changes. The great part about it, is you can pass the cursor to other procedures in the package, and it will be sitting on the same record you last processed.

Since you are actually sitting on the database with those, execution time is immensly faster than bringing the data to your desktop, or even an application server on a 100 mbit connection.

Speed is the big deal. I have stuff that can process half a billion transactions in 30 minutes in PL/SQL. That is why you need them.