Hi Preben,
Derby supports cascade delete as part of the referential action specified at
table's creation time.
Then, when using a DELETE statement to remove row(s) from the referenced table,
the DELETE operation is propagated to the dependent table. Here is an example:
CREATE TABLE dest (
id int,
PRIMARY KEY(id)
);
CREATE TABLE source (
id int GENERATED ALWAYS AS IDENTITY,
ref int REFERENCES dest(id) ON DELETE CASCADE,
PRIMARY KEY(id)
);
INSERT INTO dest VALUES (1), (2), (3);
INSERT INTO source(ref) VALUES (1), (1), (3);
DELETE FROM dest WHERE id = 1;
SELECT * FROM source;
--> will return only the row (id:3, ref:3)
Hope this helps,
Sylvain
Preben Mikael Bohn a écrit :
Hi all
I'm trying to delete all entries from a bunch of tables in my
database; from the reference manual it seems that the DELETE statement
cannot do cascading operations. So when I try to delete tables where I
have foreign key constraints I get an error like
"DELETE on table 'foo caused a violation of foreign key constraint
'bar' for key (196608). The statement has been rolled back."
In postgres I simply do "TRUNCATE TABLE tablename CASCADE"; is there
something similar in Derby?
Best regards Preben
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