Re: insert only if conditions are met?

On Fri, 2 Sep 2005, Henry Ortega wrote:

> Thanks for all your answers. Very helpful.
> What if after adding all those hours in one long transaction,
> I want to send a query to check the MONTHLY TOTAL HOURS
> (including those just entered)
> and if they exceed N number of hours, all those records added
> should *ROLLBACK*?
>
> BEGIN;
> insert..........
> insert.........
> if sum(hours)>N then ROLLBACK
> END;
>
> Is that possible? Maybe with just plain SQL? (and one transaction)
>

Just add in another where clause using AND and modify the values to sum
the hours for the entire month instead of just the day.

At least I think that would do it.

>
>
> On 8/31/05, Philip Hallstrom <postgresql(at)philip(dot)pjkh(dot)com> wrote:
>>
>>> On Wed, 2005-08-31 at 12:49 -0400, Henry Ortega wrote:
>>>> Ok. Here's TABLE A
>>>>
>>>> emp date hours type
>>>> JSMITH 08-15-2005 5 WORK
>>>> JSMITH 08-15-2005 3 WORK
>>>> JSMITH 08-25-2005 6 WORK
>>>>
>>>> I want to insert the ff:
>>>> 1.) JSMITH 08-15-2005 8 VAC
>>>> 2.) DOE 08-16-2005 8 VAC
>>>>
>>>> #1 should fail because there is already 8 hours entered as being
>>>> Worked on 08-15-2005 (same date).
>>>
>>> sorry, did not notice the duplicates before my previous reply.
>>>
>>> you could do something like
>>> insert into A select 'JSMITH','08-15-2005',8,'VAC'
>>> where
>>> 8 != (select sum(hours) FROM A
>>> WHERE emp = 'JSMITH'
>>> AND date = '8-15-2005');
>>
>> Wouldn't that fail if JSMITH had only worked 7 hours on 8-15? I'm
>> guessing he'd still want it to fail since adding that 8 hours ov VAC would
>> result in a 15 hour day... so maybe something like?
>>
>> insert into A select 'JSMITH','08-15-2005',8,'VAC'
>> WHERE
>> 8 >= 8 + (select sum(hours) FROM A
>> WHERE emp = 'JSMITH'
>> AND date = '8-15-2005');
>>
>> ?
>>
>