PL/SQL Overview and Advantages

Study Notes

PL/SQL Overview

PL/SQL stands for "Procedural Language extension of SQL," integrated with Oracle database since version 7.
It is a block-structured language with logical blocks that can nest sub-blocks.
PL/SQL functionalities are extended with each Oracle database release.
PL/SQL includes programming elements like conditions, loops, and allows the declaration of constants, variables, procedures, functions, and triggers.

Advantages of PL/SQL

Supports SQL data manipulation, conditional checking, branching, and looping.
Provides error handling capabilities with user-friendly messages for errors.
Allows variables to store intermediate query results for further processing.
Enables quick and efficient calculations, enhancing transaction performance without using the Oracle engine.
Code written in PL/SQL is portable across any hardware and operating system supporting Oracle.

Disadvantages of SQL

Lacks programming techniques for condition checking, looping, and branching necessary for data testing.
SQL statements are executed one at a time, increasing network traffic and reducing data processing speed, especially in multi-user environments.
No built-in error handling facilities in SQL.

PL/SQL Blocks

PL/SQL code is executed as grouped elements called Blocks.
Blocks contain both PL/SQL and SQL instructions, executed collectively rather than sequentially.

Structure of PL/SQL Blocks

Declaration Section:
- Optional section for declaring variables, cursors, exceptions, subprograms, and collections.
- Begins with the keyword ‘DECLARE’ (for triggers and anonymous blocks) and must precede the execution section.
Execution Section:
- Mandatory section where the actual code execution occurs.
- Contains executable statements, can include both PL/SQL and SQL code, and can have nested blocks.
- Begins with the keyword ‘BEGIN’ and must be followed by ‘END’ or an Exception-Handling section.
Exception-Handling Section:
- Handles run-time exceptions, providing a structure for responding to errors.
- Optional portion of PL/SQL blocks, structured to manage exceptions raised in the execution block.

Description

This quiz explores the fundamentals of PL/SQL, the procedural extension of SQL used with Oracle databases. It covers the structure, advantages, and disadvantages of PL/SQL, focusing on its programming capabilities and conditions for enhanced data manipulation. Test your knowledge of how PL/SQL improves transaction performance and code portability.