Multiple cascade paths

Question

Multiple cascade paths

_ms65g_

SSCommitted

Points: 1504
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July 3, 2010 at 11:19 am

#387270

Hi,
I know we cannot implement a foreign key constraint that causes a multiple cascade path.
Assume we have two tables calls "persons" and "table_2".
I create the table’s schema structures with following DDL statements:
use tempdb ;
create table person(person_nbr int not null primary key) ;
create table table_2 (row_nbr int not null primary key, sender int references person(person_nbr) on update cascade,
reciever int references person(person_nbr) /*on update cascade*/) ;
I adjust only on foreign key "CASCASE update"
But it will not be practical at all!!
The only solution foot solving the problem is using "open schema" structure?
You mean I can use this schema?
use tempdb ;
create table person(person_nbr int not null primary key, person_name varchar(500)) ;
create table table_2
(row_id int primary key identity,
row_nbr int,
person_nbr int
references person(person_nbr),
type bit,
check (type in (0, 1))
--0 = sender
--1 = receiver
) ;
And for retrieving data I should use this query:
SELECT row_nbr, MAX(CASE WHEN type = 0 THEN p.person_name END) AS sender_name,
MAX(CASE WHEN type = 1 THEN p.person_name END) AS receiver_name
FROM table_2 t
JOIN persons p
ON t.person_nbr = p.person_nbr
GROUP BY row_nbr ;
I am waiting for your solutions.
Thanks.
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The Dixie Flatline SSC Guru Points: 53354 More actions · Answer 1

I'm afraid I really don't understand your question. Could you possibly supply a little more detail? What do you mean by "practical"? Some sample data and expected outputs would be most helpful in to those trying to assist you.

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mister.magoo SSC-Forever Points: 47174 More actions · Answer 2

Can you explain why you want a cascade on updates? That column references an integer primary key in the person table - surely you will not be updating that key?

MM

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