Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions
Privacy Policy

  




 

 

Databases - Practical PostgreSQL
Previous Page Home Next Page

Code Blocks

PL/pgSQL code is organized in blocks of code. This method of organization is known as block structured code . Code blocks are entered within a SQL CREATE FUNCTION call that creates the PL/pgSQL function in the PostgreSQL database. This CREATE FUNCTION command names the new function, states its argument types, and states the return type. The function's main code block then starts with a declaration section.

All variables are declared and optionally initialized to a default value in the declaration section of a code block. A variable declaration specifies the variable's name and type. The declaration section is denoted by the DECLARE keyword. Each variable declaration is ended with a semicolon.

After declaring variables, the main body of the code block is started with the BEGIN keyword. The code block's statements should appear after the BEGIN keyword.

The END keyword designates the end of the code block. The main block of a PL/pgSQL function should return a value of its specified return type and end any sub-blocks (code blocks started within another code block) before its END keyword is reached.

Example 11-5 shows the structure of a PL/pgSQL code block.

Example 11-5. Structure of a PL/pgSQL code block

CREATE FUNCTION 
identifier
 (
arguments
) RETURNS 
type
 AS '
  DECLARE
    
declaration;

    [...]
  BEGIN
    
statement;

    [...]
  END;
' LANGUAGE 'plpgsql';

A block of PL/pgSQL code can contain an unlimited amount of sub-blocks , which are code blocks nested within other code blocks. Sub-blocks are read and interpreted in the same manner as normal blocks; hence, they may also contain sub-blocks of their own.

Sub-blocks can be useful for the organization of code within a large PL/pgSQL function. All sub-blocks must follow normal block structure, meaning they must start with the DECLARE keyword, followed by the BEGIN keyword and a body of statements, then end with the END keyword.

Databases - Practical PostgreSQL
Previous Page Home Next Page

 
 
  Published under the terms of the Open Publication License Design by Interspire