On 14 Jun 2005, at 17:52, [EMAIL PROTECTED] wrote:
My suggestion, lame as it is, would be to use a 0 (zero) in place
of the
NULL value. That way, you always have a valid entry for PARENT_ID,
you can
still identify the tops of the trees (parent_id=0) and you have gotten
around the only-one-pa
Marcus Bointon <[EMAIL PROTECTED]> wrote on 06/14/2005 12:37:18
PM:
> I have a table that uses a self join to represent simple hierarchies.
> I have a parent_id field that contains a reference to the same
> table's id field. Not all items have a parent, so parent_id is nullable.
> The problem I
-
From: Marcus Bointon [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 14, 2005 11:37 AM
To: mysql@lists.mysql.com
Subject: Foreign key constraint problem
I have a table that uses a self join to represent simple hierarchies.
I have a parent_id field that contains a reference to the same
table&
I have a table that uses a self join to represent simple hierarchies.
I have a parent_id field that contains a reference to the same
table's id field. Not all items have a parent, so parent_id is nullable.
The problem I run into is in defining the foreign key constraint - if
a parent item i
On Saturday 15 March 2003 04:08, vishnu mahendra wrote:
> create table stud(rno integer not null,
> name char(10),
> primary key(rno));
>
> create table mark(rno integer not null references
> stud,
> mark integer);
[skip]
> how is it possible.
> there is no rollno 3 in the stud table,
> then how
foreign key constraint problem:
---
create table stud(rno integer not null,
name char(10),
primary key(rno));
create table mark(rno integer not null references
stud,
mark integer);
mysql> insert into stud values(1,'a');
Query OK, 1 row affected (0.2
