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Thread: "Pretend" update

"Pretend" update

From
Perry Smith
Date:
With "make" I can do "make -n" and it just tells me what it would do but doesn't actually do anything.

How could I do that with SQL?

I want to write a really complicated (for me) SQL UPDATE statement.  I'm sure I won't get it right the first time.  Is
therean easy way to not really make the changes? 

I've thought about starting a transaction and then roll it back.  That would undo the changes.  But I won't be able to
tellwhat the changes were. 

Thank you for your time,
Perry
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Re: "Pretend" update

From
Adrian Klaver
Date:
On 10/01/2013 10:16 AM, Perry Smith wrote:
> With "make" I can do "make -n" and it just tells me what it would do but doesn't actually do anything.
>
> How could I do that with SQL?
>
> I want to write a really complicated (for me) SQL UPDATE statement.  I'm sure I won't get it right the first time.
Isthere an easy way to not really make the changes? 
>
> I've thought about starting a transaction and then roll it back.  That would undo the changes.  But I won't be able
totell what the changes were. 

Assuming you are not doing this in a function, you can. Do UPDATE, then
SELECT to see your changes or not and then ROLLBACK.

>
> Thank you for your time,
> Perry
>


--
Adrian Klaver
adrian.klaver@gmail.com

Re: "Pretend" update

From
Perry Smith
Date:
On Oct 1, 2013, at 12:23 PM, Adrian Klaver <adrian.klaver@gmail.com> wrote:

> On 10/01/2013 10:16 AM, Perry Smith wrote:
>> With "make" I can do "make -n" and it just tells me what it would do but doesn't actually do anything.
>>
>> How could I do that with SQL?
>>
>> I want to write a really complicated (for me) SQL UPDATE statement.  I'm sure I won't get it right the first time.
Isthere an easy way to not really make the changes? 
>>
>> I've thought about starting a transaction and then roll it back.  That would undo the changes.  But I won't be able
totell what the changes were. 
>
> Assuming you are not doing this in a function, you can. Do UPDATE, then SELECT to see your changes or not and then
ROLLBACK.

Ah... yes.  I forgot you can see the changes within the same transaction.  Dohhh...

Thank you very much
Perry
Attachment

Re: "Pretend" update

From
Victor Yegorov
Date:
2013/10/1 Perry Smith <pedzsan@gmail.com>

On Oct 1, 2013, at 12:23 PM, Adrian Klaver <adrian.klaver@gmail.com> wrote:

> Assuming you are not doing this in a function, you can. Do UPDATE, then SELECT to see your changes or not and then ROLLBACK.

Ah... yes.  I forgot you can see the changes within the same transaction.  Dohhh...

It is possible to use RETURNING clause of the UPDATE statement and avoid SELECT.

And yes, it is necessary to do this within a transaction and roll it back after.

--
Victor Y. Yegorov