Talk:Propagation constraint
Latest comment: 13 years ago by Intgr in topic UPDATE propagation
![]() | This article is rated Stub-class on Wikipedia's content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
|
UPDATE propagation
editI've been told that MS SQL Server will propagate primary key updates to foreign keys in referencing tables via some mechanism that's peculiar to MS SQL Server. I find it hard to believe this is even logical! Anyone heard of this? Edj0321 (talk) 17:25, 25 June 2010 (UTC)
- Any database engine that supports the ON UPDATE CASCADE clause on foreign keys can do this...
- PostgreSQL:
db=# create table foo(foo_id int primary key); db=# create table bar(foo_id int references foo (foo_id) on update cascade); db=# insert into foo values(1); db=# insert into bar values(1); db=# update foo set foo_id=2; db=# select * from bar; foo_id ------ 2 (1 row)
- MySQL (watch out for gotchas):
mysql> create table foo(foo_id int primary key) engine=InnoDB; mysql> create table bar( -> foo_id int, -> foreign key (foo_id) references foo (foo_id) on update cascade -> ) engine=InnoDB; mysql> insert into foo values(1); mysql> insert into bar values(1); mysql> update foo set foo_id=2; mysql> select * from bar; +--------+ | foo_id | +--------+ | 2 | +--------+ 1 row in set (0.00 sec)