Обсуждение: Re: [HACKERS] about NULL

On 21 May 2003 at 16:10, zhangyue wrote:

> Hi,
> How can I get the tuples one of whose attributes is NULL?
> For example,
>   First, create table tb(id int,name text);
>   Then   insert into tb values(1);
> insert into tb values(2,'Rose');
>   I want to select the tuples whose attribute name= NULL,
> How to write the sql ?

select columns from table where attribute is null;

This should have been on postgresql-general, not on hackers..

HTH

Bye
 Shridhar

--
Fourth Law of Applied Terror:    The night before the English History mid-term,
your Biology    instructor will assign 200 pages on planaria.Corollary:    Every
instructor assumes that you have nothing else to do except    study for that
instructor's course.

SELECT * FROM tb WHERE name IS NULL;

And I think it should have been on the SQL list, myself...

Shridhar Daithankar wrote:

On 21 May 2003 at 16:10, zhangyue wrote:
 

Hi,
How can I get the tuples one of whose attributes is NULL?
For example, First, create table tb(id int,name text); Then   insert into tb values(1); 
insert into tb values(2,'Rose'); I want to select the tuples whose attribute name= NULL,
How to write the sql ?   

select columns from table where attribute is null;

This should have been on postgresql-general, not on hackers..

HTH

ByeShridhar

--
Fourth Law of Applied Terror:	The night before the English History mid-term, 
your Biology	instructor will assign 200 pages on planaria.Corollary:	Every 
instructor assumes that you have nothing else to do except	study for that 
instructor's course.


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On Wednesday 21 May 2003 10:46, Shridhar Daithankar wrote:
> On 21 May 2003 at 16:10, zhangyue wrote:
> > Hi,
> > How can I get the tuples one of whose attributes is NULL?
> > For example,
> >   First, create table tb(id int,name text);
> >   Then   insert into tb values(1);
> > insert into tb values(2,'Rose');
> >   I want to select the tuples whose attribute name= NULL,
> > How to write the sql ?
>
> select columns from table where attribute is null;
>
> This should have been on postgresql-general, not on hackers..
>

SELECT * FROM tb WHERE name IS NULL;
or even
SELECT * FROM tb WHERE name=NULL;
but the second one would work only if "transform_null_equals" is set to true
in postgresql.conf