Question

I am not too familiar with database triggers and/or views. I am currently using PostgreSQL and HSQL, even though the database is not too important. I am just wondering if any database offers something like this:

I have an (example) table like this:

CREATE TABLE DUMMY_TABLE (ID INTEGER, NUMBER INTEGER);

I created a view like this:

CREATE VIEW DUMMY_VIEW AS SELECT * FROM DUMMY_TABLE WHERE NUMBER > 5;

I insert a couple of entities:

INSERT INTO DUMMY_TABLE VALUES(1,2);
INSERT INTO DUMMY_TABLE VALUES(1,10);

So of course, the DUMMY_VIEW only contains VALUES(1,10) when I call:

SELECT * FROM DUMMY_VIEW;

So now what I want to do is add a trigger to the DUMMY_VIEW that is called whenever an entity is inserted that has NUMBER > 5.

I have tried adding triggers directly to the DUMMY_VIEW in both HSQL and PostgreSQL but they say that triggers cannot be added to views.

Is this (or a functionally similar solution) possible?

Answer 1

It should be noted that PostgreSQL 9.1+ supports triggers on views. See WAITING FOR 9.1 – TRIGGERS ON VIEWS for a brief look at this.