Use records to improve readability and flexibility of your code

Suppose I've created a table to keep track of hominids:

CREATE TABLE hominids
(
   hominid_name     VARCHAR2 (100),
   home_territory   VARCHAR2 (100),
   brain_size_cm    INTEGER
)
/

I might then write code like this:

DECLARE
   l_b_hominid_name    VARCHAR2 (100) := 'Bonobo';
   l_b_brain_size_cm   INTEGER := 500;
   l_g_hominid_name    VARCHAR2 (100) := 'Gorilla';
   l_g_brain_size_cm   INTEGER := 750;
   l_n_hominid_name    VARCHAR2 (100) := 'Neanderthal';
   l_n_brain_size_cm   INTEGER := 1800;

What do you think?

I find the little voice of Relational Theory inside my head rebelling.

"All that repetition! All that denormalization! All that typing (or copy-pasting, which is even worse)!"

Surely if I should avoid having redundant data in rows of my tables, I should avoid redundant code, too?

Yes, I should.  I don't like to see long lists of declarations, especially when the names are very similar and follow a pattern. 

A fine way to avoid this kind of code is to use record types to group related variables together within a named context: the record variable. So I could rewrite the declaration section above to:

DECLARE
   l_bonobo        hominids%ROWTYPE;
   l_gorilla       hominids%ROWTYPE;
   l_neanderthal   hominids%ROWTYPE;
BEGIN
   l_bonobo.hominid_name := 'Bonobo';
   l_bonobo.brain_size_cm := 500;
   l_gorilla.hominid_name := 'Gorilla';
   l_gorilla.brain_size_cm := 750;
   l_neanderthal.hominid_name := 'Neanderthal';
   l_neanderthal.brain_size_cm := 1800;

Notice that I now move the initializations of the variable (well, record.field) values to the executable section. That's because PL/SQL does not yet offer a built-in function (in object-oriented lingo, a constructor method) for record types.

So I no longer have six declarations - just three. And, of course, if my table had 15 columns and I had declared a separate variable for each of those, I would have been able to shrink down my declarations from 45 to 3!

Still, I don't like putting all that initialization code in the main body of my block. How about if I create my own "record constructor" function, and then call that:

CREATE OR REPLACE FUNCTION new_hominid (
   name_in IN hominids.hominid_name%TYPE,
   home_territory_in IN hominids.home_territory%TYPE,
   brain_size_cm_in IN hominids.brain_size_cm%TYPE)
   RETURN hominids%ROWTYPE
IS
   l_return hominids%ROWTYPE;
BEGIN
   l_return.hominid_name := name_in;
   l_return.home_territory := home_territory_in;
   l_return.brain_size_cm := brain_size_cm_in;
   RETURN l_return;
END;
/

DECLARE
   l_bonobo        hominids%ROWTYPE := new_hominid ('Bonobo', NULL, 500);
   l_gorilla       hominids%ROWTYPE := new_hominid ('Gorilla', NULL, 750);
   l_neanderthal   hominids%ROWTYPE := new_hominid ('Neanderthal', NULL, 1800);
BEGIN
   DBMS_OUTPUT.put_line (l_neanderthal.brain_size_cm);
END;
/

Ahhhhh. Just three declarations. Default values assigned in the declaration section. All the details of the assignments hidden away behind the function header.

And when I add a new column to the table (or generally a field to a record), I can add a parameter to my new_hominid function, along with a default value of NULL, and none of my existing code needs to change (unless that new column or field is needed).

Yes, I like that better.

How about you?