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Sunday, 3 April 2016

PL/SQL Introduction

Advantages of PL/SQL

                        Tight Integration with SQL
                        Better Performance
                        Higher Productivity
                        Full Portability
                        Tight Security
                        Access to Pre-defined Packages
                        Support for Object-Oriented Programming
                        Support for Developing Web Applications and Pages
                                  Support for Developing Web Applications and Pages

You can use PL/SQL to develop Web applications and Server Pages (PSPs).

PL/SQL Block
PL/SQL is a block structured language
It is composed of one or more blocks
Types of Blocks
Anonymous Blocks: constructed dynamically and executed only once
Named Blocks: Subprograms, Triggers, etc.
Subprograms: are named PL/SQL blocks that are stored in the database and can be invoked explicitly as and when required; e.g. Procedures, Functions and Packages
Triggers: are named blocks that are also stored in the database; Invoked implicitly whenever the triggering event occurs; e.g. Database Triggers

PL/SQL Block Structure

      A PL/SQL block has the following structure

                                      Variables, cursors, user-defined exceptions, etc.
                                      SQL and PL/SQL statements

                                      Trapping Errors occurred in executable section

Note:  BEGIN & END are compulsory statements

PL/SQL Block consists of three sections

Declarative: Contains declarations of variables, constants, cursors, user-defined exceptions and types (Optional)
Executable: Contains SQL statements to manipulate data in the database and PL/SQL statements to manipulate data in the block
Exception Handling: Specifies the actions to perform when errors and abnormal conditions arise in the executable section (Optional)

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  1. Greetings Mate,

    Great info! I recently came across your blog and have been reading along.
    I thought I would leave my first comment. I don’t know what to say except that I have

    We have a weird
    issue with MSSQL 2012 on AMAZON (RDS), at one point the CPU spikes to 20 % and the 20% is now the new 0% until I change the threshold for parallelism. This means the cpu stays constant > 20% during the day. After the modification of the parameters the cpu drops and the sql server shows normal CPU signs going from 5% to 10% with some higher spikes. I have no idea why this happens and why this resolves itself when I change the max dop or the threshold for parallelism.

    Excellent tutorials - very easy to understand with all the details. I hope you will continue to provide more such tutorials.

    Ajeeth Kapoor