LewisC’s An Expert’s Guide To Oracle Technology

Ok, I know you you’ve heard of them. Heck, in some cases, you’ve been beaten over the head with them. So why   aren’t you using them?

I’ve heard some people saying that it’s easier to code without bind variables. Really? Concatenating strings,   potentially with embedded quotes and/or varying formats, is easier than using bind variables?

I got an email the other day from a reader who asked to remain anonymous. He said that he read that he should use   bind variables and understood why but wasn’t sure he understood the concept of actually implementing code with   bind variables.

In Part 1 of this series, I introduced you to the basic components and some information you need to know before using the scheduler. Today’s post will cover using the API to create some basic objects. I’ll show how to use SQL Developer to simplify some of these tasks.

Today’s post will cover creating programs and jobs.

Programs

As I said in my last scheduler post: it all starts with the program. A program is a PL/SQL procedure (can be packaged but not a function), PL/SQL block or external OS program.

You do not need to define a program if you don’t want to.

OCFS? That sure sounds familiar! OFS, OCFS? Where have a I heard that before? Oh yeah, Oracle Cluster File System! So, now Oracle has a cloud file system? Cool!

OCFS is based on ASM Cluster File System (ACFS) and ASM Dynamic Volume Manager (ADVM). It looks like the marketing material also refers to OCFS as CloudFS. The idea is to use ASM functionality with 3rd party file systems to provide simplify management and improve utilization of storage systems. More importantly, and here is where the Cloud comes in, it provides elastic provisioning.

DBMS_SCHEDULER is Oracle’s full featured scheduling solution that runs inside the database. Think of it as a complete replacement for DBMS_JOB (which I do still use occasionally but am using less and less over time). DBMS_SCHEDULER has a lot of benefits over DBMS_JOB – ability to stop a job, ability to reuse code, ability to reuse schedules, ability to chain jobs into a job streams, etc.

This post is the first of a series of posts that I will be doing on DBMS_SCHEDULER. Actually I am doing a lot of Streams work again and it was kind of a toss up as to which tool I’d blog about first.

Continuing from Part 1.

So now we have our transactional model and a basic user story:

Our first request from the business for our data mart is that they want to be able to query all of the orders by date, by customer and/or by region (state, city or country). They want to be able to aggregate (sum and average) across those items.

The first thing we need to do is talk to the business and find out exactly what that request means. Do the users want to see information about daily orders in general?

As I mentioned a while back (a loooong while back), I have been thinking about writing up how I design data marts. The problem with that is that it is a huge topic. Even converting an existing schema (which doesn’t always exist) to a data mart (star schema style), still takes plenty of behind the scenes data analysis and prepwork. Still, I am not going to take a shot at it.

I could start with a laundry list of requirements but I don’t think that would be interesting to very many people.

It was pointed out to me that I had a few errors in the previous release.  Those have been fixed and the install should go a lot smoother now.  No additional functionality here, just bug fixes.  If you tweaked the previous release to install it, you don’t need this one.

As always, you can download the new code directly from the PL/JSON SourceForge page.

Change Log:

Version: 0.6.2
Fixed exit commands in various code files
Removed the “CREATE OR REPLACE” on the string_handler.printf function

Version: 0.6.1
Added missing string_handler package

Version: 0.6
Added support for creating JSON from text input

Version 0.5
Initial release
Includes a JSON data type
Can create tables and columns of JSON
Supports API creation of JSON data type

LewisC

From the Database Geek.

PL/JSON v0.6.1 has now been released to Sourceforge.net. The reason for the .1 is that I forgot a dependency on the 0.6 release.

Anyway, PL/JSON can now create JSON via the API or through parsing a text string. The parser is implemented as a stand along package. That means you can write your own parser (or use an external procedure) if you don’t like mine. This will make it very extensible. I also plan to add PL/SQL callbacks to the parser at some point for custom processing.

Example of parsing:

SET SERVEROUTPUT ON

DECLARE
  v_json json;
  v_json2 VARCHAR2(32000) :=
   '{
      "abc": "dpkxvdvvcxz\"vxasasa   ",
      "def": 12345,
      "ghi":{"isit":true, "nope":false,"denada":true },
      "jkl": [1234, 45678.99, 121211, 21323232, 00000]
   }';
BEGIN

  v_json := json(v_json2);
  v_json.print;
END;
/

{
"abc":"dpkxvdvvcxz\"vxasasa   ",
"def":12345,
"ghi":{
"isit":true,
"nope":false,
"denada":true}
,
"jkl":[1234,45678.99,121211,21323232,0]}

Output from PL/JSON checks out on JSONLint.

From the Database Geek.

I recently needed to query all of the arguments to the various stored procedures, functions, packaged objects and types. Oracle provides all of this information in the data dictionary in the ALL_PROCEDURES and ALL_ARGUMENTS views. The problem with this is that it’s kind of kludgey to suck out all of the pertinent data.

One problem is that arguments for procedures and functions in packages is access differently than arguments for stand alone procedures and functions. What I did was combine the two calls into a single pipelined function that returned the data I needed.

From the Database Geek.

I’m not even going to try to explain why I wrote this. Let’s just say that it comes in handy on occasion.

What this very simple procedure does is use DBMS_SCHEDULER to execute a shutdown command in windows. This could easily be adapted to Unix and/or Linux.

Use at your own risk. By default you get a 30 or 60 second delay (depending on windows version, I think) before the shutdown/reboot.

If you pass FALSE in to the procedure, or don’t pass anything, the server will shutdown. If you pass in a TRUE, the server will reboot.

Paul Gallagher, of the Tardate blog, emailed me this morning (or I guess it was last night) and sent me some code to enhace ORA_Tweet.  He wrote a package to call out to an is.gd API to convert a long URL to a short URL.  The really cool thing is that he used a regular expression to find matches INSIDE the comment body.  That means that ANY URLs will be replaced with a short URL, you don’t have to call the API individually.

His API is easily called and can be used for projects other than just ORA_Tweet.  Check out his write up on the SHORTURL package:  Tweeting from your database with short urls

I updated the ora_tweet code so you can download the entire set of code if you would like.

From the Database Geek.

I recently had a requirement to populate the day dimension of a data mart (I won’t put all of the code here as it’s pretty large). That’s not that big deal but part of the requirement was to set several columns: BUSINESS_DAY_FLAG, BUSINESS_DAY_NO and BUSINESS_DAYS_REMAINING_NO.

• The BUSINESS_DAY_FLAG is Y is the date is MON-FRI and N is the date is SAT or SUN.
• BUSINESS_DAY_NO is the business day of the month. There are 5 business days per week so if the month started on a monday, the second monday would be business day 6.
• BUSINESS_DAYS_REMAINING_NO is the number of business days remaining in the month.

Recently I posted an article about ORA_Tweet, an Oracle Twitter Client. I was asked by someone reading the code why I put several variables in the BODY of the package rather than the SPEC. The question was posed something like this:

Why not put the variables in the package spec where they are modifiable? That would involve less maintenance.

I specifically put them in the body so that they are not modifiable. I don’t see public global variables as a particularly good thing. To understand why, let’s take a look at the benefits of a package.

First, you can group logical functions and procedures together.

From the database geek.

Update March 29, 2009:  PL/JSON is now available as an open source project (MIT License).  Read the FAQ at http://oracleoss.com

Do you use JSON? Do you use Oracle? How would you like to use JSON in Oracle? How would you like to store it, generate it and read it? I am creating a new JSON data type that will work like XMLType.

I am assuming you are familiar with Oracle (or you probably wouldn’t be reading this blog). If you are not familiar with JSON it is JavaScript Object Notation, a lightweight data-interchange specification. Think of it as a replacement to XML.

Get the latest source from the ORA Tweet project page at sourceforge.

I had some free time this last Saturday night (after the family was all in bed) and I wanted to do a little mini-project. I don’t get to do enough PL/SQL anymore so I like to look for utilities and smaller fun things to code. While I was thinking about it, I was also following along on twitter to the posts that the people I follow had recently made.

I decided to put together a twitter procedure that would let me make posts from the database.

I get a lot of email, and comments on blog entries, asking questions about many different topics. I am going to try to answer some of the more common questions as FAQs. Today I am starting with some NUMBER FAQs. I am specifically talking about Oracle and I am specifically talking about the NUMBER data type, not numerics in general. I’ve written about NUMBERs before.

Q: What is the difference between an INTEGER and a NUMBER.

A: INTEGER is a subtype of NUMBER. INTEGER is declared as NUMBER(38,0). That means it is a “constrained” NUMBER.

A mathematician, an accountant and an economist apply for the same job. The interviewer calls in the mathematician and asks “What do two plus two equal?”

The mathematician replies “Four.”

The interviewer asks “Four, exactly?” The mathematician looks at the interviewer incredulously and says “Yes, four, exactly.”

Then the interviewer calls in the accountant and asks the same question “What do two plus two equal?” The accountant says “On average, four – give or take ten percent, but on average, four.”

Then the interviewer calls in the economist and poses the same question “What do two plus two equal?”

The economist gets up, locks the door, closes the shade, sits down next to the interviewer and says “What do you want it to equal?”

And now for something completely different:

What is AQ?

Advanced Queues, or AQ, is Oracle’s messaging solution.

What is Replication?

According to Webster’s Online, the definition we mean is: 3 a : COPY, REPRODUCTION b : the action or process of reproducing

Replication is simply copying data from one database to another. This could be a subset of the data or a complete copy.

I’m going to use insert for my examples but any DML can be replicated.

If you create an insert trigger on a table and push data across a database link every time a record gets inserted, you’ve performed replication. Call that the poor man’s SYNCHRONOUS replication.

From the Database-Geek.

In addition to frequently being asked to recommend books for newbies to Oracle, I am also asked for guidance on certification. Basically, what materials are available and worth purchasing. I used Self Test software and the Sybex books when I was working on my certification. That was back in the 9i days. If you are working on 9i certification, I strongly recommend them.

However, I figure you are probably working on an 11g certification; 10g at least. In that case, I would guess that Sybex and Self Test are still good options, I just haven’t personally worked with the latest versions (software or books).

LewisC’s An Expert’s Guide to Oracle Technology
Is it possible to build a PL/SQL parser using nothing but PL/SQL? To answer that question, I guess I need to define “PL/SQL parser”. What would be the intention of this parser?
I would like a way to pa…

Thank you. Comments like that are exactly why I do this.

LewisC

!***! Entry Link: 10 Tips For Complete Database Newbies!***!

Wow. I’ve been toying around the idea of learning Oracle. Have read few manuals and tried my hands on 9i. But then later I moved on to .Net and now I’m back to Oracle and am looking to improve my hands on 10g. And after going thtrough your blog, it’s kinda motivating and guiding. Nice posts. Thanks a lot Lewis.

!***! Entry Link: <a href=”http://it.toolbox.com/blogs/oracle-guide/10-tips-for-complete-database-newbies-24

LewisC’s An Expert’s Guide to Oracle Technology
I needed to update some files and that meant updating some utility functions that I haven’t looked at in a long time. I decided to share a few of them today.
One of the most important aspects of PL/SQL…

I started working on a task for a project and decided that there were some very good properties that I could use to help me teach people PL/SQL and XML. I expanded a bit on the idea and ended up with a scripting language, implemented in XML, that can be passed into a PL/SQL procedure. The script can execute stored procedures, it has looping logic, conditional (CASE) logic, user defined variables, etc.

The nice thing about it is that it’s very easy to read and modify. The XML structure is also very easy to read.

Oracle provides a lot of XML functionality in the database. This entry will cover the different tools Oracle provides and future entries will get into the details of each.

The three primary XML tools that oracle provides are: XML Developers Kit (XDK), XML DB and SQL Extensions for XML (SQLX and XMLType). Below is a definition of each.

XDK

The XDK is a complete XML development toolkit that was introduced for 8i. I think the first version was labeled XDK9i but the toolkit actually was available for 8i. I remember using the beta product.

In Part 1 of this series, we talked about how Oracle objects compare to Java and how to create Oracle Objects. In Part 2, I covered we covered object comparison and type inheritance. Today, we’ll talk about polymorphism and type evolution.

Like parts 1 and 2, this will be a technical discussion.

Polymorphism

First a definition. What is Polymorphism and why is it important? One of the best definitions I have found is this link at OnJava. You can skip the part about object serialization. Not really that important to Oracle’s OO as you’re already in the database.

Let’s go back to our (most basic) calculator example.

CREATE OR REPLACE TYPE Calculator AS OBJECT (
  value NUMBER,
  MEMBER PROCEDURE print,
  MEMBER PROCEDURE add1( p_amt IN NUMBER ),
  MEMBER PROCEDURE subtract( p_amt IN NUMBER )
  )
  NOT FINAL;
/

CREATE OR REPLACE TYPE BODY Calculator AS
  MEMBER PROCEDURE print IS
  BEGIN
    DBMS_OUTPUT.PUT_LINE( TO_CHAR( value ) );
  END;

  MEMBER PROCEDURE add1( p_amt IN NUMBER )  IS
  BEGIN
    value := value + p_amt;
  END;

  MEMBER PROCEDURE subtract( p_amt IN NUMBER )  IS
  BEGIN
    value := value - p_amt;
  END;

END;
/

And our Advanced Calculator:

CREATE OR REPLACE TYPE AdvancedCalculator UNDER Calculator (
  pi FLOAT,
  CONSTRUCTOR FUNCTION AdvancedCalculator
     RETURN SELF AS RESULT ,
  MEMBER PROCEDURE multiply( p_amt IN NUMBER ),
  MEMBER PROCEDURE divide( p_amt IN NUMBER ),
  OVERRIDING MEMBER PROCEDURE print
   )
NOT FINAL;
/

This isn’t exactly the same AdvancedCalculator.

This is a continuation of Object Orientation in Oracle. I guess I should have called it the Sorcerer of OOO. This is a technical entry.

Anyway, in part 1 I covered the basics of creating an Oracle object type and showing how it compared to a Java class. Today I’m going to cover the concepts of comparing objects and Inheritance. In part 3, I will cover type evolution and Polymorphism and in part 4 I will cover Object Views and Object Tables.

Comparing Objects

Many times, you will be working with multiple instances of the same object.

I could have called this OO In Oracle: A Techie’s View. But the Sorcerer of OO is a much cooler title. You have to pronounce OO as ooh! as in Ooh and Aah!

What is OO? OO stands for Object Oriented. OOD is OO Design, OOA is OO Analysis and OOP is Object Oriented Programming. Oracle is an ORDBMS, an Object Relational Database Management System. In this article, I am going to present a sample java class and show how you would implement the same class in Oracle. This is a technical article comparing Oracle objects with Java.

It looks like the job market for Oracle is opening up. I’m seeing many of my friends find new jobs and I’m doing a lot of interviewing at work. I hope this is a trend that continues. In this entry, I share my method for interviewing Oracle resources and provide some sample interview questions and answers for developers.

Interviewing anyone can be difficult. Interviewing technical resources is very difficult. To me, probably the hardest thing is pinpointing exactly what you want this person to do. What, exactly, will this person be doing in their day-to-day job?

Regardless of any regulations you are required to meet you can implement a security and audit scheme that will cover you for most, if not all, eventualities. Having good security and auditability should be desirable regardless of regulations. It protects your business.

In parts 1 and 2, I covered the security side of it. So what do I mean by Audit? Well, auditing is knowing what’s going on in your environment. Future research requirements, accountability, error correction, etc are all covered by audit.

So how does Oracle implement audit? There are several ways you can do it: Standard Audit, Fine Grained Audit and Trigger Based Audit.