Re: Trigger to create string to inverse SQL statement

Hello:

On Thu, Mar 8, 2018 at 1:32 PM, Łukasz Jarych <jaryszek(at)gmail(dot)com> wrote:

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> i have a trigger which is added log history:
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​I'll trust it is, but I cannot really see any thing in there, it may be
better if in the future you used something like psql and pasted the data in
a text format, which people with no-so-good eyesight like me can zoom in.​

> It is possible to create additional column here with string with inversed
> SQL statement?
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> So in this case: "Delete FROM t_trig WHERE ID=1".
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> And what i want is to have possibility to loop through table and execute
> inversed sql statement for each row.
>

​It should be. For inserts it is not that difficult, for updates YMMV, it
is difficult to ​reverse a command exactly, but you get new and old values
so you could write it. For deletes just reinsert. But I doubt there is a
function which does it for you, you'll have to code something, and I
suspect it may be easier to just capture op, old and new in your triggers
and use an external program to build the inverted queries.

​Francisco Olarte.​