logic operands problem

Hello everybody,

I am having trouble finding a logic for following problem:

Should be true if:
page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3

The result should never contain 1 AND 2 in the same time.

This obviously does not work:
(page = 1 OR page = 3) OR (page = 2 OR page = 3)

This also does not work:
(page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page != 1)

Has somebody an idea how to solve this?

Thank you in advance for any help!

Merlin

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Re: logic operands problem

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Content-Transfer-Encoding: quoted-printable

what do you think about this?
if( ! (page == 1 && page == 2)){
//here
}

On Mon, Dec 7, 2009 at 4:22 PM, Merlin Morgenstern wr=
ote:

> Hello everybody,
>
> I am having trouble finding a logic for following problem:
>
> Should be true if:
> page =3D 1 OR page =3D 3, but it should also be true if page =3D 2 OR pag=
e =3D 3
>
> The result should never contain 1 AND 2 in the same time.
>
> This obviously does not work:
> (page =3D 1 OR page =3D 3) OR (page =3D 2 OR page =3D 3)
>
> This also does not work:
> (page =3D 1 OR page =3D 3 AND page !=3D 2) OR (page =3D 2 OR page =3D 3 A=
ND page !=3D
> 1)
>
> Has somebody an idea how to solve this?
>
> Thank you in advance for any help!
>
> Merlin
>
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> To unsubscribe, visit: http://www.php.net/unsub.php
>
>


--=20
Devendra Jadhav
देवेंदॠà¤° =
जाधव

--001636920c13123d57047a215143--

Re: logic operands problem

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Devendra Jadhav wrote:
> what do you think about this?
> if( ! (page == 1 && page == 2)){
> //here
> }
>

Well a simple && (and) does not help.

I want to have all results that contain either page = 1 OR page = 3, AND
in the same time I want to have the results that contain page=2 OR page= 3
, But the result should never contain page = 1 and page = 2 in the same
time.

Any further idea?





> On Mon, Dec 7, 2009 at 4:22 PM, Merlin Morgenstern
> > wrote:
>
> Hello everybody,
>
> I am having trouble finding a logic for following problem:
>
> Should be true if:
> page = 1 OR page = 3, but it should also be true if page = 2 OR
> page = 3
>
> The result should never contain 1 AND 2 in the same time.
>
> This obviously does not work:
> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>
> This also does not work:
> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND
> page != 1)
>
> Has somebody an idea how to solve this?
>
> Thank you in advance for any help!
>
> Merlin
>
> --
> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>
>
>
> --
> Devendra Jadhav
> देवेंद्र जाधव

--------------040701000006030305070801--

Re: logic operands problem

I think you could use another braket on the second example:

((page== 1 OR page== 3) AND page!= 2) OR ((page== 2 OR page== 3) AND page !=
1)

Other than that I don't think I can help.

How come the page can be 1 or 3, but not 2?
I think you could change the logic, but I don't have enough info about your
code. If page is 1 or 3, it won't be 2 (obviously), but why 2 or 3 is
acceptable?



"Merlin Morgenstern" wrote in message
news:8E.77.13248.A9EDC1B4@pb1.pair.com...
> Hello everybody,
>
> I am having trouble finding a logic for following problem:
>
> Should be true if:
> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>
> The result should never contain 1 AND 2 in the same time.
>
> This obviously does not work:
> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>
> This also does not work:
> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page !=
> 1)
>
> Has somebody an idea how to solve this?
>
> Thank you in advance for any help!
>
> Merlin


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Re: logic operands problem

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Content-Transfer-Encoding: 7bit

On Mon, 2009-12-07 at 11:52 +0100, Merlin Morgenstern wrote:

> Hello everybody,
>
> I am having trouble finding a logic for following problem:
>
> Should be true if:
> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>
> The result should never contain 1 AND 2 in the same time.
>
> This obviously does not work:
> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>
> This also does not work:
> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page != 1)
>
> Has somebody an idea how to solve this?
>
> Thank you in advance for any help!
>
> Merlin
>


I thought this might work:

(page = 3) OR (page = 1 XOR 2)

But having given it more thought, I'm not so sure. I assume from your
example that this is MySQL code and not PHP. Having said that, how can a
field of one row have more than one value? Surely `page` is either 1, 2
or 3, not two of them at once. How do you want your results pulled?
Assuming you have rows containing all three values, how do you decide
which of the pair of results you want?

Thanks,
Ash
http://www.ashleysheridan.co.uk



--=-zCJAakhFiWZF0QGyB1vx--

Re: logic operands problem

Merlin Morgenstern wrote:
> Hello everybody,
>
> I am having trouble finding a logic for following problem:
>
> Should be true if:
> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>
> The result should never contain 1 AND 2 in the same time.
>
> This obviously does not work:
> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>
> This also does not work:
> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page
> != 1)
>
> Has somebody an idea how to solve this?
>
> Thank you in advance for any help!
>
> Merlin


Surely what you need is xor (exclusive-or)
I can't believe a programmer has never heard of that!

(page==1 XOR page==2) AND page==3

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Developer fax: 01580 893399
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Re: logic operands problem

Peter Ford wrote:
> Merlin Morgenstern wrote:
>> Hello everybody,
>>
>> I am having trouble finding a logic for following problem:
>>
>> Should be true if:
>> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>>
>> The result should never contain 1 AND 2 in the same time.
>>
>> This obviously does not work:
>> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>>
>> This also does not work:
>> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page
>> != 1)
>>
>> Has somebody an idea how to solve this?
>>
>> Thank you in advance for any help!
>>
>> Merlin
>
>
> Surely what you need is xor (exclusive-or)
> I can't believe a programmer has never heard of that!
>
> (page==1 XOR page==2) AND page==3
>

HEllo Peter,

thank you for your reply. I know about XOR, but unfortunatelly I might
not know how to use it properly OR it is not aplicable on SQL. I am
trying to retrive data:
SELECT * FROM test WHERE ((page = 1 XOR page = 2) OR page = 3)

I know this is not php, but I thought the logic should be the same in
this case?!

Regards, Merlin

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Re: Re: logic operands problem

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On Mon, 2009-12-07 at 12:37 +0100, Merlin Morgenstern wrote:

> Peter Ford wrote:
> > Merlin Morgenstern wrote:
> >> Hello everybody,
> >>
> >> I am having trouble finding a logic for following problem:
> >>
> >> Should be true if:
> >> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
> >>
> >> The result should never contain 1 AND 2 in the same time.
> >>
> >> This obviously does not work:
> >> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
> >>
> >> This also does not work:
> >> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page
> >> != 1)
> >>
> >> Has somebody an idea how to solve this?
> >>
> >> Thank you in advance for any help!
> >>
> >> Merlin
> >
> >
> > Surely what you need is xor (exclusive-or)
> > I can't believe a programmer has never heard of that!
> >
> > (page==1 XOR page==2) AND page==3
> >
>
> HEllo Peter,
>
> thank you for your reply. I know about XOR, but unfortunatelly I might
> not know how to use it properly OR it is not aplicable on SQL. I am
> trying to retrive data:
> SELECT * FROM test WHERE ((page = 1 XOR page = 2) OR page = 3)
>
> I know this is not php, but I thought the logic should be the same in
> this case?!
>
> Regards, Merlin
>


This will likely retrieve all the records in the table. Is that what
your tests have shown?

Thanks,
Ash
http://www.ashleysheridan.co.uk



--=-uQD5pGfShd4Dw+5nDEii--

Re: Re: logic operands problem

I don't really get it. This is a select statement working with the datas of
one table.
A field of a record (namely "page" here) can only take one value, so it is
totally nonsense to give XOR for that field.

I think you want to select two different recordsets: one with page 1 and 3,
and another with 2 and 3, am I right?

SanTa

----- Original Message -----
From: "Ashley Sheridan"
To: "Merlin Morgenstern"
Cc: "Peter Ford" ;
Sent: Monday, December 07, 2009 12:39 PM
Subject: Re: [PHP] Re: logic operands problem


> On Mon, 2009-12-07 at 12:37 +0100, Merlin Morgenstern wrote:
>
>> Peter Ford wrote:
>> > Merlin Morgenstern wrote:
>> >> Hello everybody,
>> >>
>> >> I am having trouble finding a logic for following problem:
>> >>
>> >> Should be true if:
>> >> page = 1 OR page = 3, but it should also be true if page = 2 OR page =
>> >> 3
>> >>
>> >> The result should never contain 1 AND 2 in the same time.
>> >>
>> >> This obviously does not work:
>> >> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>> >>
>> >> This also does not work:
>> >> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page
>> >> != 1)
>> >>
>> >> Has somebody an idea how to solve this?
>> >>
>> >> Thank you in advance for any help!
>> >>
>> >> Merlin
>> >
>> >
>> > Surely what you need is xor (exclusive-or)
>> > I can't believe a programmer has never heard of that!
>> >
>> > (page==1 XOR page==2) AND page==3
>> >
>>
>> HEllo Peter,
>>
>> thank you for your reply. I know about XOR, but unfortunatelly I might
>> not know how to use it properly OR it is not aplicable on SQL. I am
>> trying to retrive data:
>> SELECT * FROM test WHERE ((page = 1 XOR page = 2) OR page = 3)
>>
>> I know this is not php, but I thought the logic should be the same in
>> this case?!
>>
>> Regards, Merlin
>>
>
>
> This will likely retrieve all the records in the table. Is that what
> your tests have shown?
>
> Thanks,
> Ash
> http://www.ashleysheridan.co.uk
>
>
>


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Re: logic operands problem

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Ashley Sheridan wrote:
> On Mon, 2009-12-07 at 11:52 +0100, Merlin Morgenstern wrote:
>> Hello everybody,
>>
>> I am having trouble finding a logic for following problem:
>>
>> Should be true if:
>> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>>
>> The result should never contain 1 AND 2 in the same time.
>>
>> This obviously does not work:
>> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>>
>> This also does not work:
>> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page != 1)
>>
>> Has somebody an idea how to solve this?
>>
>> Thank you in advance for any help!
>>
>> Merlin
>>
>>
>
> I thought this might work:
>
> (page = 3) OR (page = 1 XOR 2)
>
> But having given it more thought, I'm not so sure. I assume from your
> example that this is MySQL code and not PHP. Having said that, how can
> a field of one row have more than one value? Surely `page` is either
> 1, 2 or 3, not two of them at once. How do you want your results
> pulled? Assuming you have rows containing all three values, how do you
> decide which of the pair of results you want?
>
> Thanks,
> Ash
> http://www.ashleysheridan.co.uk
>
>


You have described the problem very well. This is exactly where I can
not find a solution.

the page number translates to the following: 1= first page 2= following
pages 3= all pages

This are the options a user has while booking a product on my site. Now
if ther is a new
client that wants to book all pages, I need to query the table to find
out if the spot is available.
The spot would be full if page 1 has more results then 3 , OR all
following pages have more then 3 results. So to find out if "all pages"
option would be available I need to query the db to retrieve all
results, that are (page = 3) OR (page = 1 XOR 2)

Am I wrong?


--------------050203070800090301000309--

Re: Re: logic operands problem

--------------090702060205030705050304
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Content-Transfer-Encoding: 7bit



Ashley Sheridan wrote:
> On Mon, 2009-12-07 at 12:37 +0100, Merlin Morgenstern wrote:
>> Peter Ford wrote:
>> > Merlin Morgenstern wrote:
>> >> Hello everybody,
>> >>
>> >> I am having trouble finding a logic for following problem:
>> >>
>> >> Should be true if:
>> >> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>> >>
>> >> The result should never contain 1 AND 2 in the same time.
>> >>
>> >> This obviously does not work:
>> >> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>> >>
>> >> This also does not work:
>> >> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page
>> >> != 1)
>> >>
>> >> Has somebody an idea how to solve this?
>> >>
>> >> Thank you in advance for any help!
>> >>
>> >> Merlin
>> >
>> >
>> > Surely what you need is xor (exclusive-or)
>> > I can't believe a programmer has never heard of that!
>> >
>> > (page==1 XOR page==2) AND page==3
>> >
>>
>> HEllo Peter,
>>
>> thank you for your reply. I know about XOR, but unfortunatelly I might
>> not know how to use it properly OR it is not aplicable on SQL. I am
>> trying to retrive data:
>> SELECT * FROM test WHERE ((page = 1 XOR page = 2) OR page = 3)
>>
>> I know this is not php, but I thought the logic should be the same in
>> this case?!
>>
>> Regards, Merlin
>>
>>
>
> This will likely retrieve all the records in the table. Is that what
> your tests have shown?
>
> Thanks,
> Ash
> http://www.ashleysheridan.co.uk
>
>

Exactly! This is unfortunatelly what happens! Any ideas how to get the
correct results?

--------------090702060205030705050304--

Re: logic operands problem

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On Mon, 2009-12-07 at 12:49 +0100, Merlin Morgenstern wrote:

>
> Ashley Sheridan wrote:
> > On Mon, 2009-12-07 at 11:52 +0100, Merlin Morgenstern wrote:
> >> Hello everybody,
> >>
> >> I am having trouble finding a logic for following problem:
> >>
> >> Should be true if:
> >> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
> >>
> >> The result should never contain 1 AND 2 in the same time.
> >>
> >> This obviously does not work:
> >> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
> >>
> >> This also does not work:
> >> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page != 1)
> >>
> >> Has somebody an idea how to solve this?
> >>
> >> Thank you in advance for any help!
> >>
> >> Merlin
> >>
> >>
> >
> > I thought this might work:
> >
> > (page = 3) OR (page = 1 XOR 2)
> >
> > But having given it more thought, I'm not so sure. I assume from your
> > example that this is MySQL code and not PHP. Having said that, how can
> > a field of one row have more than one value? Surely `page` is either
> > 1, 2 or 3, not two of them at once. How do you want your results
> > pulled? Assuming you have rows containing all three values, how do you
> > decide which of the pair of results you want?
> >
> > Thanks,
> > Ash
> > http://www.ashleysheridan.co.uk
> >
> >
>
>
> You have described the problem very well. This is exactly where I can
> not find a solution.
>
> the page number translates to the following: 1= first page 2= following
> pages 3= all pages
>
> This are the options a user has while booking a product on my site. Now
> if ther is a new
> client that wants to book all pages, I need to query the table to find
> out if the spot is available.
> The spot would be full if page 1 has more results then 3 , OR all
> following pages have more then 3 results. So to find out if "all pages"
> option would be available I need to query the db to retrieve all
> results, that are (page = 3) OR (page = 1 XOR 2)
>
> Am I wrong?
>


I'm pretty confused by your logic, but I think the only way you can
achieve what you want is with multiple queries and counts.

Thanks,
Ash
http://www.ashleysheridan.co.uk



--=-CaY1uHmT13fDT1qm9hRN--

Re: Re: logic operands problem

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Content-Transfer-Encoding: 8bit



Sándor Tamás (HostWare Kft.) wrote:
> I don't really get it. This is a select statement working with the
> datas of one table.
> A field of a record (namely "page" here) can only take one value, so
> it is totally nonsense to give XOR for that field.
>
> I think you want to select two different recordsets: one with page 1
> and 3, and another with 2 and 3, am I right?
>
> SanTa
>
Yes, you are right. Any ideas on how to do this within one query?



> ----- Original Message ----- From: "Ashley Sheridan"
>
> To: "Merlin Morgenstern"
> Cc: "Peter Ford" ;
> Sent: Monday, December 07, 2009 12:39 PM
> Subject: Re: [PHP] Re: logic operands problem
>
>
>> On Mon, 2009-12-07 at 12:37 +0100, Merlin Morgenstern wrote:
>>
>>> Peter Ford wrote:
>>> > Merlin Morgenstern wrote:
>>> >> Hello everybody,
>>> >>
>>> >> I am having trouble finding a logic for following problem:
>>> >>
>>> >> Should be true if:
>>> >> page = 1 OR page = 3, but it should also be true if page = 2 OR
>>> page = >> 3
>>> >>
>>> >> The result should never contain 1 AND 2 in the same time.
>>> >>
>>> >> This obviously does not work:
>>> >> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>>> >>
>>> >> This also does not work:
>>> >> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND
>>> page
>>> >> != 1)
>>> >>
>>> >> Has somebody an idea how to solve this?
>>> >>
>>> >> Thank you in advance for any help!
>>> >>
>>> >> Merlin
>>> >
>>> >
>>> > Surely what you need is xor (exclusive-or)
>>> > I can't believe a programmer has never heard of that!
>>> >
>>> > (page==1 XOR page==2) AND page==3
>>> >
>>>
>>> HEllo Peter,
>>>
>>> thank you for your reply. I know about XOR, but unfortunatelly I might
>>> not know how to use it properly OR it is not aplicable on SQL. I am
>>> trying to retrive data:
>>> SELECT * FROM test WHERE ((page = 1 XOR page = 2) OR page = 3)
>>>
>>> I know this is not php, but I thought the logic should be the same in
>>> this case?!
>>>
>>> Regards, Merlin
>>>
>>
>>
>> This will likely retrieve all the records in the table. Is that what
>> your tests have shown?
>>
>> Thanks,
>> Ash
>> http://www.ashleysheridan.co.uk
>>
>>
>>
>

--------------090903090408020001030704--

Re: logic operands problem

Merlin Morgenstern wrote:
> You have described the problem very well. This is exactly where I can
> not find a solution.
>
> the page number translates to the following: 1= first page 2= following
> pages 3= all pages
>
> This are the options a user has while booking a product on my site. Now
> if ther is a new
> client that wants to book all pages, I need to query the table to find
> out if the spot is available.
> The spot would be full if page 1 has more results then 3 , OR all
> following pages have more then 3 results. So to find out if "all pages"
> option would be available I need to query the db to retrieve all
> results, that are (page = 3) OR (page = 1 XOR 2)
>
> Am I wrong?

Yes I think you are! And XOR may be wrong here. XOR is a binary operator, so
think of the number as 0b0011 for 3 0b0010 for 2 and 0b0001 for 1 ...
1 XOR 2 will give a result of 0b0011 - so = 3

What you are trying to do just seems wrong in general.
'if page 1 has more results then 3' requires you count the number of page 1
records and compare with the number of page 3 records. And the same with page 2
results.

I don't think you are giving enough detail to know exactly what you are trying
to achieve, but what you are describing so far does not make sense 'logically'.
If you are trying to book a 'set' of pages but can't if one of that set is
already booked, then I don't think you can do this with a single query. You need
to check each 'page' individually. If this was room booking, then one would have
to check there are no other bookings for a day in the period for that particular
room. Or putting it another way, there are no days in the period when all rooms
are booked, but in this case you still need to know that a particular room is
available for the whole period.

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RE: Re: logic operands problem

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Content-Transfer-Encoding: 7bit

On Mon, 2009-12-07 at 12:26 +0000, Ford, Mike wrote:

> This is pretty much why SQL does not offer you the XOR operator!


Someone better tell the MySQL developers then...

http://dev.mysql.com/doc/refman/5.0/en/logical-operators.htm l


Thanks,
Ash
http://www.ashleysheridan.co.uk



--=-x6HuUyg4vs0SdZTotD/I--

RE: Re: logic operands problem

> -----Original Message-----
> From: Merlin Morgenstern [mailto:merlin_x@fastmail.fm]
> Sent: 07 December 2009 11:52
> To: "S=E1ndor Tam=E1s (HostWare Kft.)"
> Cc: Merlin Morgenstern; php-general@lists.php.net
> Subject: Re: [PHP] Re: logic operands problem
>=20
>=20
>=20
> S=E1ndor Tam=E1s (HostWare Kft.) wrote:
> > I don't really get it. This is a select statement working with the
> > datas of one table.
> > A field of a record (namely "page" here) can only take one value,
> so
> > it is totally nonsense to give XOR for that field.
> >
> > I think you want to select two different recordsets: one with page
> 1
> > and 3, and another with 2 and 3, am I right?
> >
> > SanTa
> >
> Yes, you are right. Any ideas on how to do this within one query?

If you need these two specific recordsets, I don't see how you can. You'll=
have to make two queries and do any further logic in PHP using the two set=
s of results.

XOR is a total nonsense in this situation -- as your condition is targeting=
a single, single-valued field, the value you are testing cannot possibly b=
e simultaneously both 1 and 2, so the XOR operator is essentially redundant=
and effectively the same as the OR operator. This is pretty much why SQL d=
oes not offer you the XOR operator! All of the condition variants I've seen=
in this thread so far pretty much boil down to (page=3D1 OR page=3D2 OR pa=
ge=3D3), which, as you found, returns your entire database.

Cheers!

Mike
--=20
Mike Ford,
Electronic Information Developer, Libraries and Learning Innovation,
Leeds Metropolitan University, C507, Civic Quarter Campus,=20
Woodhouse Lane, LEEDS,=A0 LS1 3HE,=A0 United Kingdom=20
Email: m.ford@leedsmet.ac.uk=20
Tel: +44 113 812 4730




To view the terms under which this email is distributed, please go to http:=
//disclaimer.leedsmet.ac.uk/email.htm

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RE: Re: logic operands problem

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Re: logic operands problem

Hey Merlin

Merlin Morgenstern wrote on 2009-12-07 11:52:
> Hello everybody,
>
> I am having trouble finding a logic for following problem:
>
> Should be true if:
> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>
> The result should never contain 1 AND 2 in the same time.
>
> This obviously does not work:
> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>
> This also does not work:
> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page
> != 1)
>
> Has somebody an idea how to solve this?

I've read the entire thread and can see that this is a MySQL query you
want to make (I was about to tell you about the == comparison and the $
in a variable in PHP).

What you want is all results containing 1,2 or 3, so make a "WHERE page
IN(1,2,3)" and use PHP logic to figure out if a free slot is available
or not. Or rewrite your booking routine (use data and time fields
instead, maybe by creating a bunch of free slots and then a booked field
with a default of "0", changed to "1" when booked)

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Re: logic operands problem

At 11:52 AM +0100 12/7/09, Merlin Morgenstern wrote:
>Hello everybody,
>
>I am having trouble finding a logic for following problem:
>
>Should be true if:
>page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>
>The result should never contain 1 AND 2 in the same time.
>
>This obviously does not work:
>(page = 1 OR page = 3) OR (page = 2 OR page = 3)
>
>This also does not work:
>(page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND page != 1)
>
>Has somebody an idea how to solve this?
>
>Thank you in advance for any help!
>
>Merlin

Merlin:

The variable "page" cannot hold two values at the same time and thus
your statement "The result should never contain 1 AND 2 in the same
time" is nonsense.

Now if you are working two variables, namely $a and $b and you want
an algorithm to solve your problem, it's simple.

if ($a + $b > 3)
{
$result = true;
}
else
{
$result = false;
}

Cheers,

tedd

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Re: logic operands problem

--------------010002000300060607070807
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Hi everybody,

thank you for all the help and thoughts. I have solved it, but I guess
it is not an elegant solution. What I do now, is simply check again for
the second case. There are 2 cases. Either first page OR all pages,
second case: following pages OR all pages.

My booking checking looks now as following:



############################################################ ####################################
# on which page will the tl be placed?
if ($data[page] == 3){ // all pages
$where_page = 'AND (page = 1 OR page = 3)'; // unfortunatelly we
have to test later on page = 2 OR page = 3. No solution inside one
query. We tried also (page=1 XOR page=2) OR page = 3
$where_page_2 = 'AND (page = 2 OR page = 3)';
}
else{ // page one or all following pages
$where_page = 'AND page = '.$data[page];
}

############################################################ ####################################

############################################################ ####################################
# find out first possible booking period
do{
// get all toplistings that are at least with one day inside the
desired booking period
$stmt= "
SELECT
*
FROM
$DB.$T54
WHERE
cat_id = '$data[cat_id]'
AND cat_type = '$data[cat_type]'
$where_page
AND
(
(start_date <= '$new_start' AND expires >=
'$new_start')
OR (start_date <= '$new_end' AND expires >= '$new_end')
OR (start_date >= '$new_start' AND start_date<=
'$new_end')
)
";
#echo $stmt.$br;
$result = execute_stmt($stmt, $link);
while ($row = db_get_row($result)){
$booked[start][] = $row->start_date;
$booked[end][] = $row->expires;
}
$possible_bookings = count($booked[start]);
// would there be more bookings then possible?
if ($possible_bookings >= $places){ // not enough space. Try
nest day
$shift = true; // shift period for one day
$reservation = 1;
$new_start = date("Ymd",strtotime($new_start." + 1 day"));
$new_end = date("Ymd",strtotime($new_end." + 1 day"));
}
else{ // enough space
unset($shift);
}
unset($booked);
} while ($shift); // shift as long as we find free space

############################################################ ####################################



############################################################ ####################################
# if client wants to book all pages, we have to try also the second
constellation
# we could not find a way to do this in one sql query
# find out if booking period has to be shifted even further due to
all pages booking
if ($page == 3){
do{
// get all toplistings that are at least with one day inside
the desired booking period
$stmt= "
SELECT
*
FROM
$DB.$T54
WHERE
cat_id = '$data[cat_id]'
AND cat_type = '$data[cat_type]'
$where_page_2
AND
(
(start_date <= '$new_start' AND expires >=
'$new_start')
OR (start_date <= '$new_end' AND expires >=
'$new_end')
OR (start_date >= '$new_start' AND start_date<=
'$new_end')
)
";
//echo $stmt.$br;
$result = execute_stmt($stmt, $link);
while ($row = db_get_row($result)){
$booked[start][] = $row->start_date;
$booked[end][] = $row->expires;
}
$possible_bookings = count($booked[start]);
// would there be more bookings then possible?
if ($possible_bookings >= $places){ // not enough space. Try
nest day
$shift = true; // shift period for one day
$reservation = 1;
$new_start = date("Ymd",strtotime($new_start." + 1
day"));
$new_end = date("Ymd",strtotime($new_end." + 1 day"));
}
else{ // enough space
unset($shift);
}
unset($booked);
} while ($shift); // shift as long as we find free space
}

############################################################ ####################################


This is rather a dirty solution. Maybe someone has an idea on how to do
it more elegant? I believe there should be one simple line that is
different instead of checking it all over again for a second time.


Any ideas?


Kim Madsen wrote:
> Hey Merlin
>
> Merlin Morgenstern wrote on 2009-12-07 11:52:
>> Hello everybody,
>>
>> I am having trouble finding a logic for following problem:
>>
>> Should be true if:
>> page = 1 OR page = 3, but it should also be true if page = 2 OR page = 3
>>
>> The result should never contain 1 AND 2 in the same time.
>>
>> This obviously does not work:
>> (page = 1 OR page = 3) OR (page = 2 OR page = 3)
>>
>> This also does not work:
>> (page = 1 OR page = 3 AND page != 2) OR (page = 2 OR page = 3 AND
>> page != 1)
>>
>> Has somebody an idea how to solve this?
>
> I've read the entire thread and can see that this is a MySQL query you
> want to make (I was about to tell you about the == comparison and the
> $ in a variable in PHP).
>
> What you want is all results containing 1,2 or 3, so make a "WHERE
> page IN(1,2,3)" and use PHP logic to figure out if a free slot is
> available or not. Or rewrite your booking routine (use data and time
> fields instead, maybe by creating a bunch of free slots and then a
> booked field with a default of "0", changed to "1" when booked)
>

--------------010002000300060607070807--