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PostgreSQL Server Programming

You're reading from   PostgreSQL Server Programming Take your skills with PostgreSQL to a whole new level with this fascinating guide to server programming. A step by step approach with illuminating examples will educate you in the full range of possibilities.

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Product type Paperback
Published in Jun 2013
Publisher Packt
ISBN-13 9781849516983
Length 264 pages
Edition 1st Edition
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Toc

Table of Contents (17) Chapters Close

PostgreSQL Server Programming
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
1. What Is a PostgreSQL Server? 2. Server Programming Environment FREE CHAPTER 3. Your First PL/pgSQL Function 4. Returning Structured Data 5. PL/pgSQL Trigger Functions 6. Debugging PL/pgSQL 7. Using Unrestricted Languages 8. Writing Advanced Functions in C 9. Scaling Your Database with PL/Proxy 10. Publishing Your Code as PostgreSQL Extensions Index

Simple "Hey, I'm called" trigger


The first trigger we work on simply sends back a notice to the database client each time the trigger is fired and provides some feedback on its firing conditions:

CREATE OR REPLACE FUNCTION notify_trigger()
  RETURNS TRIGGER AS $$ 
BEGIN 
    RAISE NOTICE 'Hi, I got % invoked FOR % % % on %', 
                               TG_NAME, 
                               TG_LEVEL, 
                               TG_WHEN, 
                               TG_OP, 
                               TG_TABLE_NAME; 
END; 
$$ LANGUAGE plpgsql;

Next, we need a table to bind this function to the following:

CREATE TABLE notify_test(i int);

And we are ready to define the trigger. As we try to be simple here, we define a trigger which is invoked on INSERT and which calls the function once on each row:

CREATE TRIGGER notify_insert_trigger
  AFTER INSERT ON notify_test
  FOR EACH ROW
EXECUTE PROCEDURE notify_trigger();Let's test it out.postgres=# INSERT INTO notify_test VALUES(1),(2)...
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