The Power of Names

Oracle PL/SQL Programming

Steven [email protected]

PL/SQL Evangelist, Dell

The Powerof Names

mailto:[email protected]


Copyright 2013 Feuerstein and Associates Page 2

What's In a Name?• A name is an abstraction, a symbol that is

associated with an underlying set of data.• A common concept in history is: knowing the

"true name" of something or someone gives one power over that thing.– Le Guin's Earthsea cycle a classic example– Let's not forget about Rumplestiltskin.– And if you know God's true name…wow!

• Names exist in a hierarchy of abstraction.– Human -> Woman -> Mother -> Joan Feuerstein



What's in a brain?• Humans constantly seek models to describe how the

brain works.– Most have failed dismally. Where art thou, AI?– Most would agree that the brain identifies and stores data,

which can be referenced by name.• Seems fairly clear that our brain is a big pattern

analysis engine, sorting through all the data our senses provide.– Build plans of action based on those patterns.– One interesting consequence: stereotyping/prejudice

unavoidable feature of "being human"?– Check out: numenta.org and On Intelligence.



Pattern Analysis and Abstraction

• Or to bring it back to our favorite species….

Everyone knows you're a person



Names in Software• Names are crucial to human efforts to

transform our world to make it more convenient and more comfortable.– But what do they do for software?

• Names are used in software in two key ways….– 1. Hide information: avoid information overload!– 2. Improve maintainability: make it easier to read

and understand code.



Hide Information• Information hiding: a key principle of software

generally and object orientation in particular.• Human brains can handle only so much data.

– We live in an age of information overload (internet, 24 hour TV, etc.).

• This is certainly true of complex software.– The closest humans come to "world creators."

• So we hide details that are not needed at this moment behind a name.



Improve Maintainability of Code• Arguably the most important (and most

neglected) aspect of software.• Factors in maintainability include:

– Self-documentation: comments are bad. :-) – Single point of definition: repetition is bad.– Ease (and associated low cost) of change over

time: spaghetti code is bad.• Let's take a look at features of PL/SQL that

relate to names.



Where Names Are Found in PL/SQL• Where are they not found?

– Software without names is, well, blobby.• Tables, views, columns• Program units and their subprograms• Types…and subtypes• Variables, constants and cursors• Labels for "unnamed" sections of code



Guidelines for An Excellent PL/SQL Name• Has no more than 30 characters. Bummer!

– And finds a nice balance between length and clarity• Does not rely on CamelNotation.

– Don't fight case insensitivity of SQL-PL/SQL!• Reflects the information hidden behind the name.

– A misleading name makes reading code extremely difficult.

• Standardize the structure of the name.– Prefixes, suffixes, singular vs. plural

get_the_name_right.sql



Program Units and Names• The starting point (leaving aside

tables and views) for all PL/SQL developers.

• Start with package names, then subprogram names, then nested subprogram names.– Package names: define an area of

functionality, into which are collected multiple procedures and functions.

– Subprogram names: procs do things, functions return things. Don't put "get" in function name!



Nested Subprograms• You can declare a procedure or

function in any declaration section.– An anonymous block– Another procedure or function

• Nested subprograms offer tremendous power to improve readability through information hiding.

"extreme" modularization -> high readability

"table of contents" for subprogram



Types and Subtypes• Oracle defines lots of "generic" types for us to

use (NUMBER, VARCHAR2, DBMS_SQL.NUMBER_TABLE, etc.).

• We can also create our own types, as well as the simple but powerful SUBTYPE.– Declare types in package specs so they can be re-

used easily.– Subtypes give application-specific names for

commonly-used declaration types.

plsql_limits.pksstring_tracker3.*



About SUBTYPEs• You can't always use %TYPE or %ROWTYPE in your

declaration.• You can, however, always define a "subtype" or

subset of an existing type with the SUBTYPE statement. SUBTYPE benefits:– Avoid exposing and repeating constraints.– Give application-specific names to types. Critical when

working with complex structures like collections of records, and nested collections.

– Apply constraints, such as numeric ranges, to the variable declared with the subtype.



Applying SUBTYPEs• Two key scenarios:

– Whenever you are about to write a VARCHAR2(N) or other constrained declaration, define a subtype instead, preferably in a package specification.

– Instead of writing a comment explaining a declaration, put the explanation into a subtype.

fullname.pksplsql_limits.pks

string_tracker3.*

DECLARE l_full_name VARCHAR2(100); l_big_string VARCHAR2(32767);

DECLARE l_full_name employees_rp.full_name_t; l_big_string plsql_limits.maxvarchar2;

Instead of this:

Writethis:



Variables, Constants and Cursors• As with program units, make sure your names

reflect the content/usage of your variable.• Use constants to hide literal values, providing

a single point of definition.• You can also declare a cursor in a package

specification (a named query, in essence).– But watch out! The cursor will persist in your

session - you must close it explicitly when done.

hardcoding.sqlno_more_hardcoding.sql

pkgcur.pkg



Labels for "Unnamed" Code Sections • Nested blocks are "anonymous".• Loops are "anonymous."• But you can give them names with labels!

– But I recommend that you make them nested subprograms instead.

– Use Toad's Refactoring tool to make sure you "do it right."BEGIN <<per_month_report>> FOR indx IN 1 .. 12 LOOP ... END LOOP per_month_report;

<<close_orders>> DECLARE l_new_local_var NUMBER := 100; BEGIN ... END close_orders;



The Power of Names• Names contain an enormous amount of

explanatory and manipulative power.• With great power, comes great responsibility.

– Thanks, Spiderman!• So first maximize opportunities to replace

complexity with a name.• Next, choose your names with care.• The result? Sparkling clear software that will

be given the name: "Excellent Stuff"



Visit and Use…

• A portal for Toad users specifically and Oracle technologists generally.– OK, and not just Oracle!

• An overload of information (blogs, whitepapers, forums, utilities, etc.) carefully hidden behind lots of names.

• PL/SQL Obsession: toadworld.com/SF, my cyberhome for all things PL/SQL!



Other Resources for PL/SQL Developerswww.plsqlchallenge.comDaily PL/SQL quiz, weekly SQL, APEX and logic quizzes. Prizes!

www.plsqlchannel.com27+ hours of detailed video training on Oracle PL/SQL

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The Power of Names

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