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
DECLARE
Variables, cursors, user-defined exceptions, etc.
BEGIN
SQL and PL/SQL
statements
EXCEPTION
Trapping
Errors occurred in executable section
END;
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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