NULLS vs Empty result in PHP

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Morning!

Just a quick question.

Say I have a column in my database that could contain NULLS, empty spaces,
or an actual value.

If I do:

$my_query = "SELECT my_column FROM my_database WHERE 1 = 1";
$my_result = ifx_query($my_query, $connect_id);

while($row = ifx_fetch_row($my_result)) {
$my_column = trim($row['my_column']);

if ($my_column != "") {
echo "Test";
}
}

The way PHP assigns the query results to the $my_column variable, wouldn't;
if ($my_column != "") not do anything for the rows that contained NULLS or
empty spaces?

--000e0cd23cb2c3cfe104743d6e88--

RE: NULLS vs Empty result in PHP

Use var_dump before processing your result.

Regards,

Samrat Kar
FRD, BARC

Tel: 022-25597295
Alternate Email: esamrat@yahoo.com


-----Original Message-----
From: Dan Shirah [mailto:mrsquash2@gmail.com]
Sent: Wednesday, September 23, 2009 5:28 PM
To: PHP General
Subject: [PHP] NULLS vs Empty result in PHP

Morning!

Just a quick question.

Say I have a column in my database that could contain NULLS, empty spaces,
or an actual value.

If I do:

$my_query = "SELECT my_column FROM my_database WHERE 1 = 1";
$my_result = ifx_query($my_query, $connect_id);

while($row = ifx_fetch_row($my_result)) {
$my_column = trim($row['my_column']);

if ($my_column != "") {
echo "Test";
}
}

The way PHP assigns the query results to the $my_column variable, wouldn't;
if ($my_column != "") not do anything for the rows that contained NULLS or
empty spaces?

No virus found in this incoming message.
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17:54:00



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Re: NULLS vs Empty result in PHP

using empty() is ´the right way to check a var for NULL or ""

however, it also depends what MySQL has got as setuo definition for empty
fields. on textfields u can define an epmty string as default.

ralph_deffke@yahoo.de

"Dan Shirah" wrote in message
news:a16da1ff0909230458o30d66186m75fc4fd0d1972601@mail.gmail .com...
> Morning!
>
> Just a quick question.
>
> Say I have a column in my database that could contain NULLS, empty spaces,
> or an actual value.
>
> If I do:
>
> $my_query = "SELECT my_column FROM my_database WHERE 1 = 1";
> $my_result = ifx_query($my_query, $connect_id);
>
> while($row = ifx_fetch_row($my_result)) {
> $my_column = trim($row['my_column']);
>
> if ($my_column != "") {
> echo "Test";
> }
> }
>
> The way PHP assigns the query results to the $my_column variable,
wouldn't;
> if ($my_column != "") not do anything for the rows that contained NULLS
or
> empty spaces?
>



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Re: Re: NULLS vs Empty result in PHP

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Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

>
> using empty() is =B4the right way to check a var for NULL or ""
>
> however, it also depends what MySQL has got as setuo definition for empty
> fields. on textfields u can define an epmty string as default.
>
> So say these are the first three results of my query:

"some text" //The column actually has data
" " //The column contains a series of spaces
"NULL" //The column contains a NULL value

As long as I trim() the result, if (!empty()) would skip any results where
the column contains " " OR "NULL", correct?

--000e0cd25d82f3ee2004743e4e0e--

Re: Re: NULLS vs Empty result in PHP

Ralph Deffke wrote:
> using empty() is ´the right way to check a var for NULL or ""

Empty will also match a string containing 0. And, to me, that doesn't at
all seem empty :)

Cheers,
Rob.
--
http://www.interjinn.com
Application and Templating Framework for PHP

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RE: Re: NULLS vs Empty result in PHP

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RE: Re: NULLS vs Empty result in PHP

On Wed, 2009-09-23 at 16:34 +0300, Mert Oztekin wrote:
> if it can take only numeric values u can use is_numeric()
>=20
> also i suggest that you not to use nulls in dbs. instead, use "not null" =
and "default value" property. Its more simple and more effective for both m=
anaging your database and coding your program.
>=20
>=20
> -----Original Message-----
> From: Robert Cummings [mailto:robert@interjinn.com]
> Sent: Wednesday, September 23, 2009 4:28 PM
> To: Ralph Deffke
> Cc: php-general@lists.php.net
> Subject: Re: [PHP] Re: NULLS vs Empty result in PHP
>=20
> Ralph Deffke wrote:
> > using empty() is ´the right way to check a var for NULL or ""
>=20
> Empty will also match a string containing 0. And, to me, that doesn't at
> all seem empty :)
>=20
> Cheers,
> Rob.
> --
> http://www.interjinn.com
> Application and Templating Framework for PHP
>=20
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> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
>=20
>=20
>=20
> ________________________________
> Bu mesaj ve ekleri, mesajda gönderildiği belirtilen kişi/k=
işilere özeldir ve gizlidir. Size yanlışlıkla ula=
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esajı sisteminizden siliniz. Mesaj ve eklerinin içeriği ile =
ilgili olarak şirketimizin herhangi bir hukuki sorumluluğu bulunm=
amaktadır. Şirketimiz mesajın ve bilgilerinin size deği=
şikliğe uğrayarak veya geç ulaşmasından, b=C3=
=BCtünlüğünün ve gizliliğinin korunamamasÄ=
=B1ndan, virüs içermesinden ve bilgisayar sisteminize verebilece=
ği herhangi bir zarardan sorumlu tutulamaz.
>=20
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n anyway to your computer system.

Or you could leave the database with the nulls in, and cast the value
explicitly as an integer with intval() or floatval() which will always
give you a numeric value.

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




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Re: Re: NULLS vs Empty result in PHP

--000e0cd23cb269cdc004743f7048
Content-Type: text/plain; charset=ISO-8859-1

>
> if it can take only numeric values u can use is_numeric()
>
> also i suggest that you not to use nulls in dbs. instead, use "not null"
> and "default value" property. Its more simple and more effective for both
> managing your database and coding your program.
>
>

It's a CHAR (60) field.

This database has been around for close to a decade and I'm not the DBA for
it. And with several billion records and 1000's of tables I don't see them
getting updated/changed. (The gov't doesn't like change)

--000e0cd23cb269cdc004743f7048--

Re: NULLS vs Empty result in PHP

Dan Shirah wrote:
> Morning!
>
> Just a quick question.
>
> Say I have a column in my database that could contain NULLS, empty spaces,
> or an actual value.
>
> If I do:
>
> $my_query = "SELECT my_column FROM my_database WHERE 1 = 1";
> $my_result = ifx_query($my_query, $connect_id);
>
> while($row = ifx_fetch_row($my_result)) {
> $my_column = trim($row['my_column']);
>
> if ($my_column != "") {
> echo "Test";
> }
> }
>
> The way PHP assigns the query results to the $my_column variable, wouldn't;
> if ($my_column != "") not do anything for the rows that contained NULLS or
> empty spaces?
>

From reading the other responses to this thread, it seems that you want to
"skip" or "exclude" rows in the results where my_column === null.

If this is correct, why not do it in the SELECT statement to begin with?

$my_query = "SELECT my_column FROM my_database WHERE my_column IS NOT NULL";

That should do it.


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Re: NULLS vs Empty result in PHP

--000e0cd5a2a6f8f88604743fcfc9
Content-Type: text/plain; charset=ISO-8859-1

>
> From reading the other responses to this thread, it seems that you want
> to
> "skip" or "exclude" rows in the results where my_column === null.
>
> If this is correct, why not do it in the SELECT statement to begin with?
>
> $my_query = "SELECT my_column FROM my_database WHERE my_column IS NOT
> NULL";
>
> That should do it.
>

I want to exclude the rows that might be NULL, "" (empty), or " "
(empty series of spaces)

From all of the input so far, it seems that using trim() on the variable and
then use empty() is the best way to pick all three types up.

--000e0cd5a2a6f8f88604743fcfc9--

Re: NULLS vs Empty result in PHP

On Sep 23, 2009, at 9:48 AM, Dan Shirah wrote:

>>
>> From reading the other responses to this thread, it seems that you
>> want
>> to
>> "skip" or "exclude" rows in the results where my_column === null.
>>
>> If this is correct, why not do it in the SELECT statement to begin
>> with?
>>
>> $my_query = "SELECT my_column FROM my_database WHERE my_column IS NOT
>> NULL";
>>
>> That should do it.
>>
>
> I want to exclude the rows that might be NULL, "" (empty), or
> " "
> (empty series of spaces)
>
> From all of the input so far, it seems that using trim() on the
> variable and
> then use empty() is the best way to pick all three types up.

I don't think you're using mysql, but your selected db may have a
similar option. I would do the work in the sql.

$sql = "SELECT * FROM `table` WHERE TRIM(`column`) <> '' AND `column`
IS NOT NULL";
$result = query($sql);
while ($row = fetch_row ($result)) {
echo "Not empty, multiple spaces or NULL!";
}
?>

So, if you have any extraneous spaces, they will be removed. It also
accounts for nulls. No work is required by PHP to determine the values
you need. Just use what it returns. This should work.

Hope this helps.
~Philip


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Re: NULLS vs Empty result in PHP

On Wed, Sep 23, 2009 at 11:35 AM, Philip Thompson
wrote:
> On Sep 23, 2009, at 9:48 AM, Dan Shirah wrote:
>
>>>
>>> From reading the other responses to this thread, it seems that you want
>>> to
>>> "skip" or "exclude" rows in the results where my_column ===3D null.
>>>
>>> If this is correct, why not do it in the SELECT statement to begin with=
?
>>>
>>> $my_query =3D "SELECT my_column FROM my_database WHERE my_column IS NOT
>>> NULL";
>>>
>>> That should do it.
>>>
>>
>> I want to exclude the rows that might be NULL, "" (empty), or " =A0 =A0 =
=A0 =A0"
>> (empty series of spaces)
>>
>> From all of the input so far, it seems that using trim() on the variable
>> and
>> then use empty() is the best way to pick all three types up.
>
> I don't think you're using mysql, but your selected db may have a similar
> option. I would do the work in the sql.
>
> > $sql =3D "SELECT * FROM `table` WHERE TRIM(`column`) <> '' AND `column` I=
S NOT
> NULL";
> $result =3D query($sql);
> while ($row =3D fetch_row ($result)) {
> =A0 =A0echo "Not empty, multiple spaces or NULL!";
> }
> ?>
>
> So, if you have any extraneous spaces, they will be removed. It also
> accounts for nulls. No work is required by PHP to determine the values yo=
u
> need. Just use what it returns. This should work.
>
> Hope this helps.
> ~Philip
>
>
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> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>

Another thought might be to convert the nulls into another value

select field1, field2, ISNULL(field3,'-') from table where ...

would convert the nulls into hyphens

--=20

Bastien

Cat, the other other white meat

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