Skip to main content

Object Types and Object-Oriented Development with PL/SQL: the Series

Find below the list of my blog posts in a series on working with object types (a.k.a, classes) in Oracle Database and, specifically, PL/SQL.

This series is not intended to offer an in-depth training on object-oriented development; instead, it introduces basic O-O concepts and shows how they are implemented in Oracle Database with PL/SQL.

Introduction to Object Types, Part 1
Object Types and Inheritance, Part 2
Object Types Methods, Part 3
Using Object Types in Relational Tables, Part 4

Each post also contains a link to a LiveSQL script, so you can try out all the code yourself.

Still to come:

Comparison Methods, Part 5
Dynamic Polymorphism, Part 6

Comments

Popular posts from this blog

Get rid of mutating table trigger errors with the compound trigger

When something mutates, it is changing. Something that is changing is hard to analyze and to quantify. A mutating table error (ORA-04091) occurs when a row-level trigger tries to examine or change a table that is already undergoing change (via an INSERT, UPDATE, or DELETE statement). In particular, this error occurs when a row-level trigger attempts to read or write the table from which the trigger was fired. Fortunately, the same restriction does not apply in statement-level triggers.

In this post, I demonstrate the kind of scenario that will result in an ORA-04091 errors. I then show the "traditional" solution, using a collection defined in a package. Then I demonstrate how to use the compound trigger, added in Oracle Database 11g Release1,  to solve the problem much more simply.

All the code shown in this example may be found in this LiveSQL script.
How to Get a Mutating Table ErrorI need to implement this rule on my employees table:
Your new salary cannot be more than 25x th…

Quick Guide to User-Defined Types in Oracle PL/SQL

A Twitter follower recently asked for more information on user-defined types in the PL/SQL language, and I figured the best way to answer is to offer up this blog post.

PL/SQL is a strongly-typed language. Before you can work with a variable or constant, it must be declared with a type (yes, PL/SQL also supports lots of implicit conversions from one type to another, but still, everything must be declared with a type).

PL/SQL offers a wide array of pre-defined data types, both in the language natively (such as VARCHAR2, PLS_INTEGER, BOOLEAN, etc.) and in a variety of supplied packages (e.g., the NUMBER_TABLE collection type in the DBMS_SQL package).

Data types in PL/SQL can be scalars, such as strings and numbers, or composite (consisting of one or more scalars), such as record types, collection types and object types.

You can't really declare your own "user-defined" scalars, though you can define subtypes from those scalars, which can be very helpful from the perspective…

Table Functions, Part 1: Introduction and Exploration

Please do feel encouraged to read this and my other posts on table functions, but you will learn much more about table functions by taking my Get Started with PL/SQL Table Functions class at the Oracle Dev Gym. Videos, tutorials and quizzes - then print a certificate when you are done!


Table functions - functions that can be called in the FROM clause of a query from inside the TABLE operator - are fascinating and incredibly helpful constructs.

So I've decided to write a series of blog posts on them: how to build them, how to use them, issues you might run into.

Of course, I am not the first to do so. I encourage to check out the documentation, as well as excellent posts from Adrian Billington (search for "table functions") and Tim Hall. Adrian and Tim mostly focus on pipelined table functions, a specialized variant of table functions designed to improve performance and reduce PGA consumption. I will take a look at pipelined table functions in the latter part of this seri…