IS NULL returns Empty set, but I have empty items

[Norman Khine]

Hello,
I don't know what I am missing, but I have this:

mysql SELECT url FROM product WHERE url IS NULL;
Empty set (0.05 sec)

mysql SELECT url FROM product WHERE product_Id = 67;
+--+
| url  |
+--+
|  |
+--+
1 row in set (0.00 sec)

what goes with this, how can i ensure that this is NULL?

here is the table structure

http://pastie.org/1066140

thanks for any insight.


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Re: IS NULL returns Empty set, but I have empty items

[Andy Wallace]

blank is not null... I'll bet if you did

SELECT url FROM product WHERE url = '';

you'll get a row or three. If the field was NULL, your product_id
select would look like:

 +--+
 | url  |
 +--+
 |NULL  |
 +--+

andy

Norman Khine wrote:

Hello,
I don't know what I am missing, but I have this:

mysql SELECT url FROM product WHERE url IS NULL;
Empty set (0.05 sec)

mysql SELECT url FROM product WHERE product_Id = 67;
+--+
| url  |
+--+
|  |
+--+
1 row in set (0.00 sec)

what goes with this, how can i ensure that this is NULL?

here is the table structure

http://pastie.org/1066140

thanks for any insight.




--
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iHOUSEweb, Inc.
awall...@ihouseweb.com
(866) 645-7700 ext 219
--
There are two ways to build software:
Make it so simple that there are obviously no bugs,
or make it so complex that there are no obvious bugs.

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Re: IS NULL returns Empty set, but I have empty items

[Dan Nelson]

In the last episode (Jul 29), Norman Khine said:
 I don't know what I am missing, but I have this:
 
 mysql SELECT url FROM product WHERE url IS NULL;
 Empty set (0.05 sec)
 
 mysql SELECT url FROM product WHERE product_Id = 67;
 +--+
 | url  |
 +--+
 |  |
 +--+
 1 row in set (0.00 sec)
 
 what goes with this, how can i ensure that this is NULL?

Your url may be the empty string .  If it was really NULL, you would see
NULL in the resultset.  Try

SELECT * FROM product WHERE url=

-- 
Dan Nelson
dnel...@allantgroup.com

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Re: IS NULL returns Empty set, but I have empty items

[Norman Khine]

thank you, this makes sense.

On Thu, Jul 29, 2010 at 11:29 PM, Dan Nelson dnel...@allantgroup.com wrote:
 In the last episode (Jul 29), Norman Khine said:
 I don't know what I am missing, but I have this:

 mysql SELECT url FROM product WHERE url IS NULL;
 Empty set (0.05 sec)

 mysql SELECT url FROM product WHERE product_Id = 67;
 +--+
 | url  |
 +--+
 |      |
 +--+
 1 row in set (0.00 sec)

 what goes with this, how can i ensure that this is NULL?

 Your url may be the empty string .  If it was really NULL, you would see
 NULL in the resultset.  Try

 SELECT * FROM product WHERE url=

 --
        Dan Nelson
        dnel...@allantgroup.com

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-- 
˙uʍop ǝpısdn p,uɹnʇ pןɹoʍ ǝɥʇ ǝǝs noʎ 'ʇuǝɯɐן sǝɯıʇ ǝɥʇ puɐ 'ʇuǝʇuoɔ
ǝq s,ʇǝן ʇǝʎ
% .join( [ {'*':'@','^':'.'}.get(c,None) or
chr(97+(ord(c)-83)%26) for c in ,adym,*)uzq^zqf ] )

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