Re: [SQL] DEFAULT confusion

On Wed, Sep 08, 1999 at 02:39:46AM +0000, Hroi Sigurdsson wrote:
> Hello postgresql'ers (how do you pronounce that?).
> 
> Suppose i have the following sequence, table and index:
> 
> CREATE SEQUENCE stuff_seq; 
> CREATE TABLE stuff (
>         id      INTEGER DEFAULT NEXTVAL('stuff_seq') NOT NULL,
>         name    TEXT,
>         number  INTEGER
> );
> CREATE UNIQUE INDEX stuff_id ON tabel(id); 
> 
> Then to properly insert rows i have to
> 
> INSERT INTO tabel VALUES (NEXTVAL('tabel_seq'), "sometext", 123);
> 
> I can't just
> INSERT INTO tabel VALUES (NULL, "something", 123);

Multiple errors here, BTW: your table name is "stuff" not "tabel", and
"something" is a field or table name, 'something' is a quoted string.

> 
> Then what is the point of the DEFAULT clause? In other words: How do I
> get away with not specifying anything for id? And how (if

Herouth and Thomas Mack have already pointed out the correct INSERT
syntax, (good rant, Herouth!) so I won't deal with this here.

INSERT INTO stuff (name,number) VALUES ('something',123);


> possible/recommendable) do I force the id value to be nothing but
> NEXTVAL('stuff_seq'), ie. not just an arbitrary number?

Here you enter the realm of triggers. To use them, you have to write
a procedure that can be used as a 'BEFORE INSERT' trigger. However,
I think you'll find properly formated INSERT statements will do most of
what you want.  I just don't insert into my serial columns, ever.

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