mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-12-21 08:29:39 +08:00
d489fdfc7f
works with a new policy in cascade mode . Please Read README.MAX . I do not know if you are the author of refint.c , but if not please tell me who is . Thank you ( excuse me for my bad english) . Massimo Lambertini massimo.lambertini@everex.it
77 lines
2.7 KiB
Plaintext
77 lines
2.7 KiB
Plaintext
|
|
Here are general trigger functions provided as workable examples
|
|
of using SPI and triggers. "General" means that functions may be
|
|
used for defining triggers for any tables but you have to specify
|
|
table/field names (as described below) while creating a trigger.
|
|
|
|
1. refint.c - functions for implementing referential integrity.
|
|
|
|
check_primary_key () is to used for foreign keys of a table.
|
|
|
|
You are to create trigger (BEFORE INSERT OR UPDATE) using this
|
|
function on a table referencing another table. You are to specify
|
|
as function arguments: triggered table column names which correspond
|
|
to foreign key, referenced table name and column names in referenced
|
|
table which correspond to primary/unique key.
|
|
You may create as many triggers as you need - one trigger for
|
|
one reference.
|
|
|
|
check_foreign_key () is to used for primary/unique keys of a table.
|
|
|
|
You are to create trigger (BEFORE DELETE OR UPDATE) using this
|
|
function on a table referenced by another table(s). You are to specify
|
|
as function arguments: number of references for which function has to
|
|
performe checking, action if referencing key found ('cascade' - to delete
|
|
corresponding foreign key, 'restrict' - to abort transaction if foreign keys
|
|
exist, 'setnull' - to set foreign key referencing primary/unique key
|
|
being deleted to null), triggered table column names which correspond
|
|
to primary/unique key, referencing table name and column names corresponding
|
|
to foreign key (, ... - as many referencing tables/keys as specified
|
|
by first argument).
|
|
Note, that NOT NULL constraint and unique index have to be defined by
|
|
youself.
|
|
|
|
There are examples in refint.example and regression tests
|
|
(sql/triggers.sql).
|
|
|
|
To CREATE FUNCTIONs use refint.sql (will be made by gmake from
|
|
refint.source).
|
|
|
|
# Excuse me for my bad english. Massimo Lambertini
|
|
#
|
|
#
|
|
# New check foreign key
|
|
#
|
|
I think that cascade mode is to be considered like that the operation over
|
|
main table is to be made also in referenced table .
|
|
When i Delete , i must delete from referenced table ,
|
|
but when i update , i update referenced table and not delete like unmodified refint.c .
|
|
|
|
I made a patch that when i update it check the type of modified key ( if is a text , char() i
|
|
added '') and then create a update query that do the right think .
|
|
|
|
For my point of view that policy is helpfull because i do not have in referenced table
|
|
loss of information .
|
|
|
|
|
|
In preprocessor subdir i have placed a little utility that from a SQL92 table definition,
|
|
it create all trigger for foreign key .
|
|
|
|
|
|
the schema that i use to analyze the problem is this
|
|
|
|
create table
|
|
A
|
|
( key int4 not null primary key ,...) ;
|
|
create table
|
|
REFERENCED_B
|
|
( key int 4 , ... ,
|
|
foreign key ( key ) references A --
|
|
);
|
|
|
|
|
|
|
|
|
|
|
|
|