Re: [INTERFACES] selectecting not null varchars.

On Thu, Feb 24, 2000 at 02:04:40PM -0600, Ed Loehr wrote:
> Joseph Shraibman wrote:
> >
> > select * from directory where h != null ;
> > ... gets you this:
> > ERROR: parser: parse error at or near ";"
>
> Postgresql's SQL "not equal" operator is "<>"...Try this:
>
> select * from directory where h <> null;

Which is still throw an error. and the SQL standard way to test for
NOT NULL is:

SELECT * FROM directory WHERE h IS NOT NULL;

Here's an example:

test=> \d test
Table = test
+----------------------------------+----------------------------------+-------+
| Field | Type | Length|
+----------------------------------+----------------------------------+-------+
| date | int4 default now ( ) | 4 |
| t | text | var |
+----------------------------------+----------------------------------+-------+
test=> insert into test (t) values ('');
INSERT 869922 1
test=> select * from test;
date|t
---------+-----
949357548|two
949357551|later
951424534|
-1|one
951424715|
(5 rows)

test=> select * from test where t is not null;
date|t
---------+-----
949357548|two
949357551|later
-1|one
951424715|
(4 rows)

test=>

test=> select * from test where length(t) >0;
ERROR: Null input to textlen

test=> select * from test where t is not null and length(t) >0;
date|t
---------+-----
949357548|two
949357551|later
-1|one
(3 rows)

test=>

Ross
--
Ross J. Reedstrom, Ph.D., <reedstrm(at)rice(dot)edu>
NSBRI Research Scientist/Programmer
Computer and Information Technology Institute
Rice University, 6100 S. Main St., Houston, TX 77005