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PL/SQL Puzzle: What code can be removed?

I published a PL/SQL puzzle on Twitter on November 6 2019. I asked the following question:
Which lines of code can be removed (either entirely or in part) from the block below and not affect the output of the program in any way?
I neglected to mention in my original tweet a few important assumptions:
  1. You are running this code on Oracle Database 10g or higher.
  2. Server output is turned on.
  3. Whitespace (spaces, tabs, new-lines) don't count.
Here's the code. I will publish it as an image, just as I did on Twitter, so that you can give it a go yourself, before taking a look at the answers from me and others below that.
Check out the Twitter conversation for all the answers that were submitted. It's a fun read!

Here are the full lines that I believe can be removed:

2 - There is not need to declare the iterator used in a FOR loop, numeric or cursor versions.

7 - There is no need to declare an "empty" collection to be used to initialize l_objects.

10 - Collections are empty after declaring, always. So no reason to delete.

12 - 15 - Invoking the LAST method on an empty collection always returns NULL, so that call too DBMS_OUTPUT.PUT_LINE will never happen.

17 - This line has no impact on the behavior of the program because SELECT-BULK COLLECT-INTO always wipes out whatever was in the target collection before filling it.

28 - You don't need - and shouldn't use - an EXIT statement inside a FOR loop. It will automatically terminate when all the index values in the collection have been touched.

And here are pieces of code that can be removed from remaining lines:

5 - We do not have to declare this as an associative array. We can remove "INDEX BY PLS_INTEGER", which makes it a nested table. A SELECT-BULK COLLECT-INTO always initializes and extends nested tables and varrays

8 - ":= l_empty" There is no need to initialize a collection with an empty one. It is automatically set to that state.

In which case, the end result is nothing more than this:
DECLARE
   TYPE objects_t IS TABLE OF all_objects.object_name%TYPE;
   l_objects   objects_t;
BEGIN
     SELECT object_name
       BULK COLLECT INTO l_objects
       FROM all_objects
      WHERE object_name LIKE '%TABLE%'
   ORDER BY object_name;

   FOR indx IN 1 .. l_objects.COUNT
   LOOP
      DBMS_OUTPUT.put_line (l_objects (indx));
   END LOOP;
END;
You can run (and play around with) both versions on LiveSQL with this script.

Did I miss anything? Do you disagree with any of my removals?




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Comments

  1. guestartNovember 10, 2019 at 9:42 PM

    I’ve solved my own confusion and replied to you by Twitter. Now my current question is how to write a plsql procedure comparing the output content of two types of PLSQL codes?

    ReplyDelete

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