Re: conditional execution of insert/update-s

On 2009-01-22, Dmitry Teslenko <dteslenko(at)gmail(dot)com> wrote:
> Hello!
> Question is what's the easiest way to implement conditional execution
> of insert/update-s via psql interface?
>
> As far as I know there's following options:

> 1) create function in procedural language (plpgsql, for example);
> then call that function

> 2) update ... where <conditon>;
insert ... (select ... where <condition>);

> not sure here if <condition> can be unrelated to the table being modified
> by update/insert statement;

they can be unrelated

> Are there alternatives?

here's one but it's messy when the condition is false.

BEGIN;

SELECT expression_which_causes_an_exception_when_condition_fails;

statements...;

COMMIT;

the advantage of this is that it can be used with DDL statements.