Обсуждение: null value of type java.sql.Time

Occasionally I want to store a null value for my java.sql.Time--> Time
column in Postgresql.
update event set game_clock=null where event_id=1;

 I can retreive the record with the null value (type Time) if I select
on the primary key,
    select game_clock from event where event_id = 1;

but when I try to select on the null column value, I get zero records.
     select * from event where game_clock=null;

How can I retreive records with null values for a column?
thanks,
Phil

phil campaigne wrote:
> Occasionally I want to store a null value for my java.sql.Time--> Time
> column in Postgresql.
> update event set game_clock=null where event_id=1;
>
> I can retreive the record with the null value (type Time) if I select on
> the primary key,
>    select game_clock from event where event_id = 1;
>
> but when I try to select on the null column value, I get zero records.
>     select * from event where game_clock=null;
>
Try
select * from event where game_clock is null;

A null value cannot be used in a comparison since it's undefined. You
have to explicitly query for something that has no value, hence the
different syntax.

Regards,
Thomas Hallgren

Try:
  SELECT * FROM event WHERE game_clock IS NULL;

Greg Williamson
DBA
GlobeXplorer LLC

-----Original Message-----
From: phil campaigne [mailto:pcampaigne@charter.net]
Sent: Monday, November 22, 2004 2:33 PM
To: pgsql-general@postgresql.org
Subject: [GENERAL] null value of type java.sql.Time


Occasionally I want to store a null value for my java.sql.Time--> Time
column in Postgresql.
update event set game_clock=null where event_id=1;

 I can retreive the record with the null value (type Time) if I select
on the primary key,
    select game_clock from event where event_id = 1;

but when I try to select on the null column value, I get zero records.
     select * from event where game_clock=null;

How can I retreive records with null values for a column?
thanks,
Phil



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Try:

select * from event where game_clock IS NULL


- Greg

>Occasionally I want to store a null value for my java.sql.Time--> Time
>column in Postgresql.
>update event set game_clock=null where event_id=1;
>
> I can retreive the record with the null value (type Time) if I select
>on the primary key,
>    select game_clock from event where event_id = 1;
>
>but when I try to select on the null column value, I get zero records.
>     select * from event where game_clock=null;
>
>How can I retreive records with null values for a column?
>thanks,
>Phil