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Re: Passing a WHERE clause by trigger to a function - Mailing list pgsql-general

From Melvin Call
Subject Re: Passing a WHERE clause by trigger to a function
Date
Msg-id CADGQN57Tvw-fwF4uDoAV_httOODPUPbqYoDvmfxU66vyAo44qQ@mail.gmail.com
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In response to Re: Passing a WHERE clause by trigger to a function  (David Johnston <polobo@yahoo.com>)
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Ah, just create user-defined functions that take the ID as a parameter and have the user call them, instead of a trigger function, eh? I think I like that better because I can then have separate update and delete functions, with descriptive names. I can do that, and I guess I was looking at this the wrong way. Thanks a million!


On Tue, Jun 4, 2013 at 7:47 AM, David Johnston <polobo@yahoo.com> wrote:
Melvin Call wrote
> But I still have a question in that I'd like to know if I can pass the
> WHERE clause to the function so it can examine the query? Or will I have
> to
> test for the potential of acting on more than one row?

You can write a function that takes a text/varchar and builds a dynamic SQL
query that then is executed...but I highly advise against it. Basically you
open yourself to SQL injection attack vectors and passing in a where clause
to a function is a very non-intuitive and cumbersome API.

What you likely want are functions that do what you want and take a person
id as an input.  Let the user decide the best way to obtain that person id.

David J.






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