1. Oracle PL/SQL Programming Steven Feuerstein steven.feuerstein@software.dell.com PL/SQL Evangelist, Dell steven.feuerstein@software.dell.com The Power of Names

2. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 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

3. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 3 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.

4. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 4 Pattern Analysis and Abstraction Or to bring it back to our favorite species…. Everyone knows you're a person

5. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 5 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.

6. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 6 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.

7. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 7 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.

8. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 8 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

9. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 9 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

10. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 10 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!

11. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 11 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

12. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 12 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.pks string_tracker3.*

13. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 13 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.

14. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 14 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.pks plsql_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: Write this:

15. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 15 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.sql no_more_hardcoding.sql pkgcur.pkg

16. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 16 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 > FOR indx IN 1.. 12 LOOP... END LOOP per_month_report; > DECLARE l_new_local_var NUMBER := 100; BEGIN... END close_orders;

17. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 17 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"

18. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 18 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!

19. Oracle PL/SQL Programming Copyright 2013 Feuerstein and AssociatesPage 19 Other Resources for PL/SQL Developers www.plsqlchallenge.com www.plsqlchallenge.com Daily PL/SQL quiz, weekly SQL, APEX and logic quizzes. Prizes! www.plsqlchannel.com 27+ hours of detailed video training on Oracle PL/SQL www.stevenfeuerstein.com Sign up for monthly PL/SQL newsletter